RYUKA & PARTNERS > Patent Services > Japanese Patent Process

Requirements for filing in Japan

An applicant in Japan may claim priority based upon a patent application filed in any other country that is a signatory of the Paris Convention or the TRIPS agreement.
A Japanese application may be filed with a copy of the specification in English or Japanese, drawings, where necessary, and the following information:

Name and address of inventor(s)
Name and address of assignee(s)
Priority right date and country
Priority application number (if assigned)

Note: For a PCT national entry, we will obtain the above information, claims and specification from the PCT publication, if it was published in English. Please simply inform us of the PCT application number (and publication number for the confirmation).

Priority Document

A certified priority document must be filed within one year and four months from the first filing date of a priority-based application. When priority is based upon a European Patent Office (EPO) application, the priority document need not be filed because of an electronic transfer system established between the EPO and the Japanese Patent Office (JPO).

Power of Attorney

The JPO does not require a power of attorney for a patent attorney to file a patent application. A power of attorney is required if the invention is finally rejected and appealed, or if the patent is granted, opposed and responded. If such courses of action occur, our policy is to supply a power of attorney form to the client accompanied with our instructions.

Language of Application

Although all JPO proceedings are performed in the Japanese language, it is possible to file an initial patent application in English. In this case, a Japanese translation must be filed within two months of the initial filing date along with an additional fee. Though the filing date for the application will be that of the English application, it is the Japanese translation that will be examined. The English specification can be used as a basis for making minor word corrections to the Japanese specification, although the English specification itself may not be amended.

Electronic filing

The JPO facilitates electronic filing of patent applications and charges a substantial data-entry fee for paper applications. PCT applications, however, may not be filed electronically.


JPO rules are rather lenient regarding the form of a specification. The detailed explanation of the invention must describe the invention in a manner sufficiently clear and complete for the invention to be carried out by a person having ordinary skill in the art.

Japanese applications typically follow the following format:

  • Industrial field of application
  • Prior art
  • Problems that the invention is to solve
  • Means of solving the problems
  • Embodiments of the invention
  • Effects of the invention

In addition, as much information as possible should be included in the body of the specification. This is advisable because the JPO is very strict about the introduction of new matter in an application and rarely allows new claims in the application unless the language is specifically recited in the body of the specification.

Japanese claim practice

There is no limit on the number of claims. However, each claim beyond the first requires additional official fees for substantive examination and maintenance. As a consequence of the additional fees Japanese patents tend to average fewer claims than their corresponding US or European patents.
We, however, encourage inclusion of claims drafted with an eye toward maximizing licensing fees and potential damage awards. Specific claims which encompass the most profitable potential uses for the patented technology should also be included.

“Provisional” applications

While the JPO does not have a formal system for provisional applications as exists in the US, it is possible to file patent applications provisionally in Japan.
Japanese patent applications can claim domestic priority based on earlier filed Japanese patent applications. Embodiments, drawings, and claims can be added in new patent applications. The first application will automatically be abandoned without examination if a new application claims a domestic priority based on the first application.
In the above, the first application merely needs to satisfy formalities such as an existence of a claim. For example, by repeating the title of the invention in claim 1, this formality can be satisfied. By disclosing the most important embodiment with such a simple claim, an earlier filing date can be obtained. This first application therefore has the same effect as a US provisional application.
Please also note that this first application can be a priority base for those applications filed outside Japan.

PCT Applications

As in other countries, the national phase in Japan must be an exact translation of the originally filed PCT application. It is therefore important for those drafting PCT applications to consider the patent situation in all countries in which they intend to nationalize. A pre-filing review of PCT applications should be conducted to ensure that the original PCT applications have been prepared with Japanese patent practice in mind.
The costs associated with entering the Japanese national phase can be reduced by entering the national stage with only the original application, and not including any amendments made under PCT Article 19 or 34. While PCT rules do require that translations of all Articles 19 and 34 amendments be filed when entering a national stage, the only effect of not filing these amendments is that the amendments themselves are lost; the status of the application itself is not jeopardized. As discussed above, Japanese patent practice allows ample opportunities for amending a specification during the national phase. Most applicants request examination in Japan after receiving the results of prosecution in Europe or the US and can, therefore, use that knowledge to decide which amendments to include in Japan.

Nationalization Deadline

The due date for nationalizing the PCT application into Japan is 30 months from the priority date, regardless of whether or not a Preliminary Examination was requested.

Publication (Laying Open)

In Japan, all applications are laid open (published in the Patent Office Official Gazette) 18 months after their filing or priority date, whichever is earlier. After the application has been published, any third party may submit relevant prior art to the JPO. This article proposes using this procedure to obtain stronger patents for applicants.
An applicant may also request early publication of the patent application at any time so long as certain conditions have been met, including submission of priority documents and a Japanese language translation of an application filed in a foreign language. Withdrawal of a request for expedited publication is not permitted and, generally, the application is published about three months after the request is filed.
Provisional patent protection is available based on a published application. A notice letter may be sent to potential infringers demanding compensation for the unauthorized exploitation of a claimed invention, as published, which is enforceable after issuance of a patent. Accordingly, in certain situations, the expedited publication procedure should be used as a means for an early notice letter to potential infringers. Such an approach can serve to enhance damage awards and bring potential infringers to the negotiating table.


Request for Examination

The JPO will not examine a patent application until a request for examination is filed with official fees, which are based on the number of claims. Now applicants have three years from the filing date in Japan to file such a request.
If a request for examination is not filed by the deadline, the application will be deemed withdrawn. There is no remedy for recovering an application that is deemed withdrawn. A third party may request examination of any laid open patent, in which case, the JPO will notify the applicant.

Process Chart

Divisional Application can be filed in the steps showing “Div.”
It can also be filed after an allowance, if the case has not been appealed.
Response periods are shorter for the applicants in Japan.

Accelerated Examination

Examination can be accelerated for any Japanese patent application having a corresponding foreign application. To accelerate the examination, the applicant must provide a copy of at least one search or examination report. When an accelerated examination is requested, a first Office Action is usually issued within four months, as compared to about one year or more for normal applications.

Voluntary Amendments

As long as no new matter is introduced, voluntary amendments can be entered before the first office action and within the response period for the office actions. When filing a Request for Appeal, amendments can be filed within 30 days after filing the Appeal.
New Matter
The JPO, like most patent offices around the world, will not allow applicants to introduce new matter into the application during prosecution of an application. The definition of what constitutes new matter is very strict in Japanese practice.
Generally, unless specific parallel wording can be found within the specification as first filed, it is difficult to add such wording to the claims. When the applicant can show that the wording of the specification clearly infers such language, it is sometimes possible to add the language to the claims.
A certain amount of repetitious text using varied terms and expressions should be included in most specifications. This provides multiple avenues for future claim amendments. This approach should also be considered when drafting PCT applications to be filed overseas because support for the Japanese national phase application must be in the original PCT application.

Information Providing Practice

Japan does not have a formal system equivalent to the US’s Information Disclosure Statement system. Japan does, however, have a procedure for any party to provide a JPO examiner with relevant prior art for a patent application under consideration by providing copies of relevant documents to the JPO. This system, known as the information providing practice, was developed to allow parties with relevant knowledge or information in a certain field, primarily potential competitors, to alert the examiner of prior art not considered in examination of an application.
Applicants may also use the information providing practice effectively to ensure that the result of a patent application’s prosecution is a strong patent, which withstands opposition or invalidity trial. Such a patent is a valuable licensing resource since competitors will invariably search for prior art which is relevant to a patent before agreeing to a license. Prior art cited in search and examination reports should be filed as a type of Information Disclosure Statement in all cases, to ensure that the resulting patent will withstand an opposition or invalidation trial and to provide the best opportunities for licensing.

Detailed Description of the Invention

Enablement and inventive step requirements are stricter in Japan than in the US. The intermediate concept that is narrower than US claims, but still broader than specific examples helps in obtaining broader Japanese patents. Please see the below examples of the intermediate concept.

Please note that such description can be added by filing a domestic priority application that is similar to the CIP in the US, if the domestic priority application is filed within one year from the US first priority date.

Example (How, When and What)
(1) choose A —> How to choose A.
(2) renew —> When to renew.
(3) status —> What status.

Applicants who take advantage of this practice will be able to license or enforce their patents faster and more effectively in Japan.

Rejection by the Examiner (Office Action)

Japan has a first-to-file system. After reviewing an application, a JPO examiner will issue a Notice of Allowance or an Office Action, citing reasons why the application was rejected. Grounds for rejecting an application are listed below.

  • New matter was introduced into the application by amendment
  • Applicant is a resident of a country which does not grant reciprocal privileges to Japanese residents
  • Non-statutory subject matter
  • Lack of novelty
  • Lack of inventive step
  • The applicant was not the first one to file a patent application for the claimed invention
  • The claimed invention is disclosed in a prior patent application filed by another applicant and later published
  • The invention is liable to contravene public order, morality or public health
  • Application was not filed by all the joint owners
  • The patent was granted contrary to the provisions of a treaty
  • The specification does not describe the invention in a manner sufficiently clear and complete for the invention to be carried out by a person having ordinary skill in the art to which the invention pertains
  • The allowed claims are not (i) supported by the specification; and (ii) clear, concise, and written according to patent rules
  • Unity of the invention is not satisfied
  • An English language patent application was originally filed, and the Japanese language translation of the English version includes matter which was not disclosed in the English version
  • Applicant is not the inventor and has no right to obtain a patent

Japanese Patent Law section 29(1), which relates to novelty of an invention, was amended and became effective in 2000 to state that a patent cannot be granted for an invention publicly known or practiced beyond Japan’s borders. Therefore, an invention which is publicly demonstrated or sold in the United States, for example, before a US priority application was filed, may be barred from patent protection. Simultaneously, the amended law broadens the definition of publication to include not only documents printed on paper, but also material publicly distributed over electronic communications networks with wide access such as the internet. These changes apply similarly to the obviousness requirements defined in Patent Law section 29(2).

The Office Action will list a deadline, usually three months for foreign applicants, within which a response can be filed. A single three-month extension may be automatically obtained upon application. If the examiner is not convinced by the reply, a second, final rejection or decision of rejection will be issued. Amendments in response to a final rejection are limited in their scope.

Interviewing the Examiner

Interviewing the examiner is often an excellent way to help the examiner understand the invention. Often the examiner will suggest allowable claims.


An applicant may appeal a decision of rejection of a patent application. A Notice of Appeal must be filed within 90 days from the final rejection, and any amendments to the application must follow within 30 days after that.
The primary examiner will first consider the patent application and new amendments. If he or she still does not believe the application to be allowable, it will then be reviewed by an appeal board which typically consists of three examiners.

Registration and Publication

Once allowance is made and the issue fee is paid, the patent comes into existence as the patent is entered in the Patent Register. At this time, a patent number will be assigned and a Certificate of Patent will be sent to the applicant.
The term of a patent is 20 years from the Japanese filing date. The contents of the patent as entered in the Patent Register will be published in the Patent Gazette.


In Japan, once a patent has been granted, it is published for opposition in the Patent Gazette. Any third party may file an opposition to the grant of a patent within six months of publication for opposition. The grounds for an opposition are similar to the grounds for rejection of an application by an examiner. In an opposition, however, grounds based on joint ownership, unity of the invention, claims not conforming with patent rules, and lack of right to obtain a patent are not applicable.
As with an appeal, an opposition is most commonly heard by a group of three examiners. The patent owner will be given an opportunity to amend the specification or claims to the extent permitted after a final Office Action.
Because of the availability of the opposition tool, and the relative ease with which it may be applied, it may be inadvisable in certain circumstances to send warning letters related to a newly granted patent until after the expiration of the opposition period. Likewise, patent holders should factor the opposition period into the timing of entering into licensing negotiations with potential infringers.

Invalidity appeal

In Japan, any third party having a commercial interest adversely affected by a patent may begin proceedings to initiate an invalidity trial. Unlike, for example, the procedure in the United States, Japanese invalidity trials are heard by a JPO appeal board. These trials are very common in Japan, and highlight the need for patent applicants to ensure the strength of a patent before attempting to enforce it.
Grounds for initiating an invalidity trial are similar to the grounds for an examiner’s rejection of an application. However, grounds based on the claims conforming with patent rules requirements and unity of the invention are not available in an invalidity trial. A patent owner’s loss of foreign priority or benefits of the provisions of a treaty, and failure of corrections to the specification or claims to meet with statutory requirements are additional bases for initiating an invalidity trial.
In an invalidity trial, the patent owner will always be given an opportunity to narrow the claims through amendment to avoid invalidation of the entire patent. One of the reasons that dependent claims, which are narrower than an independent claim, are not always necessary in Japanese practice is that in the event additional prior art is presented in an invalidity trial, the patent owner can simply narrow the existing claims to eliminate that art. The invalidity appeal will be delayed pending review of an amendment. Accordingly, we advise that a reasonable number of narrower claims should be included at issuance of a patent.
Infringement litigation underway in court may be stayed pending the results of an invalidity trial. This period can last two years or more.

Licensing and Litigation


Patent attorneys in Japan may act as agents on behalf of clients for negotiating and making contracts. Patent specifications should be prepared with an eye toward future favorable licensing terms. Specifications filed with a licensing goal in mind could be more than twice the number of pages compared to those drafted without licensing considerations. This is because the additional language strengthens the patents and makes licensing a much more attractive option for potential infringers than litigation.
In Japan, all exclusive licenses must be registered with the JPO, following which the licensee has the right to sue for infringement.


The remedy for infringement includes injunctions and compensation for damages.

Indirect infringement of a patent right occurs when a third party makes, uses, sells, offers to sell, or imports an article that can be used only for the manufacture of a patented product or for working a patented process. Because it is very difficult to prove the exclusive use of the technology, indirect infringement is very rarely recognized by courts in Japan.

Doctrine of Equivalents (DOE)

Japan recognizes a doctrine of equivalents, with the most recent precedent on that doctrine having been set by the Supreme Court in a 1998 decision in the case of Tsubakimoto Seiki v Tei Eichi Kei.
In Tsubakimoto, the Supreme Court stated that an accused product would be regarded as being equivalent to a claimed invention, even if a specific claim element were missing, when:
  • The element is not an essential feature of the claimed invention;
  • The claimed invention achieved the object and effect of the invention even after the element is replaced with a feature in the accused product;
  • The replacement would have been obvious when the accused product was made, to a person having ordinary skill in the art to which the invention pertains;
  • The accused product was not identical to or obvious from the prior art; and
  • The accused product does not correspond to one which was intentionally excluded from the claim during its prosecution


Japan’s Patent Law states that the objective of the law is “to promote Japan’s industry.” In recent years, the JPO has often announced that its position is ‘pro-patent rights.’ Indeed, recent amendments to Japanese Patent Law have generally strengthened patent protection in Japan.
The JPO, courts and congress are strengthening Intellectual Property rights in Japan. These trends will continue and enhance the value of inventions for nurturing new industries. Apart from the traditional Japanese approach for protecting many small improvements, a strategic approach for protecting core inventions with an eye for enforcement will become more important.
Shared vision is created only through genuine communication with clients. When we understand our clients we contribute our thought, and new IP strategies are created. With this new vision, new energy starts its life. We enjoy moving with our clients toward this new vision!

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If you require any more information or have any questions, please feel free to contact us. We welcome the challenge of difficult issues and the setting of new standards.