About Us

To Colleagues in Patent Firms From Yamaguchi & Associates in Japan

We Have A Long History
What if you asked a patent attorney in Japan to file a patent application, and a few years later, you would no longer be able to contact them? You would be held accountable to your client.
It also happens in Japan that some patent firms dissolve or disappear in a short period of time.
Against such a background, our firm was established decades ago in 1977, and since then, we keep accumulating experiences and know-hows on patents, designs and trademarks gaining the confidence from all over the world. You can trust us to follow through.

We Provide Careful Advices
If it is a first time for you to file a patent application in Japan, how would you explain about the Japanese patent system to your client?
We welcome very elementary questions about intellectual property system in Japan.
Initially, we started at the same level.
So, it is very close to home. Sometimes we attend to your questions and requests even in disregard of our profit. And we try to do so as soon as possible.

Individualized Approach
During intermediate procedures, for example, we propose suggestions to increase the possibility of registration from the stand point of your firm and your client as much as possible. We would never submit a translated document automatically without reviewing it.
You can satisfy your client.
Moreover, your client can cut wasteful expenditure.

Advantages of Middle-size Firm
There are some advantages of being a mid-size firm.
We can coordinate closely among different departments, and as a result, we can provide precise and rapid response to you and your client.
Instead of being compartmentalized by person in charge, all of us deal with your cases with care as if they were our own.

We Follow Up Other Firms’ Cases
If a patent attorney in Japan gives up your case or you can no longer locate him, you would be be held accountable to your client.
Sometimes we receive and recover such cases.
Such follow-up starts with organizing deficient documents, which requires a lot of work and is troublesome. However, in many cases, we cannot charge appropriately for such work.
However, we are not thinking about just our immediate profit.

We Are Looking Forward To Seeing You
Based on our experiences, we know the importance of building trust through face-to-face communication.
We would like to make an opportunity to meet you by visiting your country or welcoming you to our office whenever possible.
You can visit our office just by walking 10 minutes from Tokyo Station in the capital of Japan.
Please contact us when you visit Japan. We are looking forward to seeing you.

A Stress Free !
We hope now you are interested in working with us.
If you entrust us with filing a patent/utility model/design/trademark application in Japan, you will be free from stress. Besides, your client will be happy.
We are looking forward to hearing from you.

Sakuo Yamaguchi, Patent Attorney
Chairman of Yamaguchi Patent and Law Firm/ Yamaguchi and Associates

Business guide

Patents, Utility Models, Designs, Trademarks

Intellectual property is similar to real property in respect to the fact that you need to submit a notification to a government agency – the Patent Bureau in this case – when you assign, rent or license the property.
Patent laws, regulations and systems differ around the world. Yamaguchi and Associates staff is knowledgeable in many systems throughout the world and we have contacts around the globe to assist you in obtaining patent rights wherever you want.

Patent application

In a capitalist society where free competition is the principle, the only thing that allows monopoly is the intellectual property system. Please use it for your business.

Utility model registration

A major legal amendment was made on April 1, 2005, which eased restrictions on the exercise of rights. In particular, products with short product lifespans have become more valuable.

Design registration

In order to obtain a design right for a product design, it is necessary to apply for design registration with the Japan Patent Office and receive design registration.

Trademark registration

In order to gain the advantage of accumulated brand power, it is necessary to apply for trademark registration with the Japan Patent Office and receive trademark registration.

International Applications

It has always been a policy of Yamaguchi & Associates to send its staff to Europe, America and other countries around the world. 

Papers, Publications, Seminars

Providing intellectual property information

Intellectual property cases in Japan

Yamaguchi and Associates presents some cases related to the intellectual properties in Japan such as patent, design, trademark and unfair competition.


The name of “Haccho-bori Doshin” originates from public dormitories which existed in the Edo period (early17th century to mid-19th century) and housed 300 police officers, referred to as Yoriki or Doshin, of the town magistrate’s office located in the Haccho-bori district.

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Tokyo Kensetsu Kaikan 1F, 2-5-1 Hacchobori, Chuo-ku, Tokyo 104-0032, Japan

10 minutes walk from Tokyo Station