Ohtsuka Patent Office

Ohtsuka Patent Office is an IP law firm founded in 1974 and located in central Tokyo, with a wealth of experience helping some of the world’s greatest innovators to develop and protect their IP assets. The firm enjoys fantastic feedback from clients old and new, among them some of the most recognisable global brands in industries spanning from telecommunications to pharmaceuticals. Ohtsuka is a high-quality, high-volume, active firm.

Ohtsuka provides one-stop services covering the entire range of issues pertaining to the IP field, including patent drafting and prosecution, patent litigation, consultation, opinion work, prior art searches and prosecution of trademarks and designs. In particular, it has developed a team highly skilled in delivering a seamless service for international clients interested in securing IP assets in Japan. Ohtsuka’s goals are to provide both international and domestic clients with a flexible, client-oriented service, maintaining clear and smooth communication throughout to keep them in the loop and in control of their patents.


Ohtsuka’s team consists of a staff of more than 86, including patent attorneys, former Japan Patent Office (JPO) examiners and engineers educated in a number of the world’s top academic institutions and with experience working at some of Japan’s leading companies. Their expertise covers a wide variety of fields, including computer and business equipment, software, telecommunications and mobile communications, image and signal processing, internet and e-commerce, semiconductor technologies, medical devices, automobiles, polymer technologies, pharmaceuticals and biotechnologies.

Many of the firm’s attorneys are Japanese/English bilingual and the team further includes native English speakers. This diverse and well-integrated team is passionate about clients’ technologies.

Patent prosecution

Ohtsuka provides the following services for both domestic and foreign clients:

  • patent drafting;
  • patent prosecution before the JPO;
  • trials at the JPO;
  • appeals to the IP High Court;
  • opinion work and evaluations;
  • prior art searches;
  • patent litigation;
  • resolution of disputes relating to patents, trademarks, copyrights and other intellectual property (through litigation or arbitration);
  • infringement litigation;
  • invalidation proceedings;
  • consultation concerning patent licensing and patent strategies in view of Japanese practice;
  • evaluation of trademark registrability and infringement clearance searches;
  • trademark registrations and counselling on trademark and related matters; and
  • patent acquisitions, transfers and due diligence checks.



Over the past 10 years, Ohtsuka has obtained over 14,000 patent registrations in Japan in a wide range of high-tech fields. A large portion of these belong to foreign clients – evidence of their confidence in Ohtsuka. From the all-Japanese environment in communicating with the JPO, Ohtsuka takes the initiative to provide the appropriate information in clear English in a timely sense to each client and always in a cost-conscious manner. Moreover, Ohtsuka is no stranger to innovative patent prosecution strategies, having obtained important patents which have contributed to changes in the examination guidelines at the JPO and patents which have formed the basis of some cases of key interest within the IT field. Ohtsuka has also represented clients in landmark cases before the IP High Court.


Our litigation teams, tailored to handle cases in the telecommunications, software, medical and mechanical technical fields, have proven experience working as patent attorneys in cooperation with appropriate law firms to bring our clients exceptional results. Our teams have been particularly successful in Japanese-style litigation because of our in-depth technological understanding accumulated through extensive patent prosecution.

Ohtsuka’s vision

With ever-evolving technologies, the world of intellectual property is prone to swift changes. Ohtsuka strives to stay up to date with the latest court cases and judgments so as to provide clients with the best possible patents and patent strategies for the future. The firm believes in the importance of keeping clients informed, and has held a number of seminars to highlight the similarities and differences between trends in patent prosecution procedure and court decisions in the United States, Europe and Japan.

Contact details

Ohtsuka Patent Office
Seventh Floor Shuwa Kioicho Park Building
3-6 Kioicho Chiyoda-ku
Tokyo 102 0094

Professional contacts

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