Japan's patent system is regulated by the Patent Law.

Scope of protection
The Patent Law offers protection for “inventions”. The law defines “invention” as "highly creative technological ideas utilizing laws of nature". The scope of protection extends to such fields as mechanical engineering, chemical engineering, electronics, biotechnology, computer programs and business methods.

Patentability
Patent is granted only for such invention that satisfies the standards of (i) industrial applicability, (ii) novelty and (iii) inventive step.

Novelty
The following inventions (a), (b) and(c) are considered not to be novel.
　Before filing a patent application,
(a) an invention publicly known or worked in Japan or a foreign country
(b) an invention described in a distributed publication in Japan or a foreign country
(c) an invention available publicly through an electric telecommunication line in Japan or a foreign country.

Exceptions to Lack of Novelty
An invention, which has fallen under above-mentioned (a), (b) and (c) as a result of an act of the person, or against the will of the person, who has the right to obtain a patent registration, shall be deemed not to have lost novelty, on condition that the application has been filed by the said person within six months from the date on which the patent first fell under either of (a), (b) or (c).

First-to-file rule
The Japanese patent system is based on a first-come, first-served rule. Companies and individuals of a PCT signatory country may apply for Japanese patent in accordance with the PCT procedure. Conventional priority, also, can be claimed within 12months from the date of the earlier application.

Introduction of Information Disclosure of Prior Arts
A patent applicant must disclose information on prior arts in the detailed explanation of invention in the specification, if he knows the prior arts when filing a patent application. The introduction of this system intends speedy and accurate examination.

Request for Examination
JPO starts examination of patentability only after a request for examination is filed with JPO. The term for requesting an examination is three years from the filing date. Non-requested application shall be deemed withdrawn. Examination usually takes 1 to 2 years from the date of filing request of examination.

laid-open publication
All patent applications shall be disclosed by JPO in its official patent gazette after one year and six months from the filing date, or earlier if requested by the applicant. Such disclosure is called "laid-open" and is made without substantial examination of the application. Once the application is disclosed, the applicant is entitled to conditional right to claim compensation against a person who utilized the invention. The amount of compensation is equivalent to that of ordinary license royalty with regard to the utilization in the period that starts when the person becomes aware of the patent application and ends when the patent is granted.

Patent Fee and Duration
After the applicant pays the patent fee for the first 3 years, the patent right shall become effective upon registration. The term of a patent is 20 years from the filing date of the application.

Term for Entering PCT National Phase
The term for entering PCT national phase in Japan is 30 months from a priority date. The grace period for filing a translation document is 2 months from the date of filing a document for entering a national phase in Japan.