Making sense of the Japanese Patent Numbering System

Confused about patent application numbers?  Here's our handy guide.

All new filings in Japan are given an initial application number. For domestic and Paris Convention filings, application numbers are issued as soon as the patent application is filed in Japan.  It may take PCT filings entering the Japan national phase a few extra days or weeks to get theirs.

Application Number in Japanese and English
Application numbers read 特願2022-XXXXXX in Japanese and JP2022-XXXXXX (or, in full, Japanese Patent Application No. 2022-XXXXXX) in English - the first 4 digits are the year of filing, which is followed by 6 more digits. 

For PCT applications that have entered the Japanese national phase, the 6-digit number starts with a 5. So, JP2018-512345 indicates a PCT nationalized application filed in 2018.

This is how this application number appears on the Japanese searchable database J-PlatPat. (https://www.j-platpat.inpit.go.jp/) Note that application numbers are only searchable on the site once they’ve been published.



Before 2000- the Japanese calendar

To complicate matters, application numbers before 2000 were based on the Japanese calendar. The Japanese calendar marks the eras of chronological emperors and is still more commonly used in business and daily life than the western one. 

The most relevant imperial eras for our purposes are Showa (昭和) 1-64 (1926-1989) and Heisei (平成) 1-31 (1989-2019). Thus, for example, Japanese patent applications filed in Showa 1 are written S01-XXXXXX (昭01-XXXXXX), and Heisei 1 filings are written H01-XXXXXX (平01-XXXXXX).

You may still see such applications cited in office actions. You can work out the western dates by looking online – which most Japanese patent attorneys also have to do! Thankfully, this system finished in Heisei 11 (1999).

Publication Number

Publication

After a certain period of time, applications are published (or “laid open for public viewing”) in the patent gazette and on the JPO’s online database (J-PlatPat), and receive a publication number to replace the initial application number above. Once published, an application is searchable by third-parties.  Note that publication does not mean the application has been formerly examined yet (see our Q&A for more details on Examination.)

Publication timing?

The timing of publication depends on the type of application. Domestic and Paris Convention filings are published 18 months after filing.  PCT applications that have entered the national phase in Japan are published on average about 7-8 months after submission of their Japanese translations.  PCT translations have to be filed within two-months of national entry. 

Publication Number in English

In simplest form, all publication numbers follow the same format as application numbers, i.e., JP + date (Japanese or western calendar) + 6-digits.  However, English publication numbers include an “A” at the end to distinguish them from application numbers—so JP2021-511223A for example.

Publication Number in Japanese

In Japanese, publication numbers differ according to whether they are domestic/Paris Convention applications or applications based on PCT applications entered in Japan.  For our purposes:

• Domestic/Paris derived applications are known as "Kokai" publications, or "unexamined patent publications" in Japanese. They begin with 特開, which is commonly written as "Japanese Laid Open Patent Publication No.” in offices actions translations, etc. 
• Applications derived from PCT applications entered at the Japan national phase are called "Kohyo" publications or "National Publications" in Japanese. They begin with 特表 - translated in full as “Japanese Patent Gazette Laid-open Publication No.”. 

To illustrate using our example above: Application number JP2018-512345 was published as JP2018-526753A (or Japanese Patent Gazette Laid-open Publication No. JP2018-526753), or 特表2018-526753 in Japanese.

Patent Number

After publication, examination and allowance, the application will be registered and issued with a 7-digit patent number. A ‘B’ is added to the simplified number in English, so JPXXXXXXXB (Japanese Patent No. XXXXXXX). In Japanese, a patent is written 特許XXXXXXX (tokkyo).

Thus, in our example, JP2018-526753A received the patent number JP6644482B (特許6644482.)

Here is the published patent JP6644482B document in Japanese, which includes the application number, publication number and the patent number.

BONUS QUESTION: Very good, but when can a third party know my application has been filed in Japan?