Company names in Japan (商号) are governed by a combination of statutes that together define what you can and cannot register. Understanding these rules at the legal level prevents rejected registrations and protects against future legal challenges.
The three primary legal sources are the Companies Act (会社法), the Commercial Registration Act (商業登記法), and the Unfair Competition Prevention Act (不正競争防止法). Each addresses a different aspect of naming.
Every company must include its entity type in its name. A Kabushiki Kaisha must include "株式会社" and a Godo Kaisha must include "合同会社." This designation can appear at the beginning or end of the name, and the choice must be specified in the articles of incorporation.
A company that is not a KK may not use "株式会社" in its name, and vice versa.
No person or entity may use a name that would create the false impression that it is a company when it is not. This protects the public from confusion.
A company may not use a name that misleads the public into believing it is a well-known different company. This provision targets intentional impersonation and brand confusion. Violators may face injunction and damages claims.
The Legal Affairs Bureau enforces character restrictions through registration examination procedures. The Ministry of Justice guidelines specify the permitted character sets:
Permitted characters:
Prohibited elements:
The Commercial Registration Act prohibits registering a company with an identical name at an identical registered address as an existing company. This is a narrow prohibition — it applies only at the same address, not nationwide.
Even if a name passes registration, it can create legal liability if it causes confusion with an established business. The Unfair Competition Prevention Act provides remedies for businesses whose names or marks are infringed. This is separate from the registration process but essential for long-term name security.
MmowW's Name Checker screens your proposed name against the following:
Use our free tool to check your compliance instantly.
Try it free →Founder using old kanji variants: Some kanji that appear on older family records are not in the modern jinmei-yō or jōyō kanji sets accepted for registration. The checker identifies characters that may not be accepted by the Legal Affairs Bureau's systems.
International brand with registered trademark filing in Japan: The brand "NovaTech" is trademarked in the US. The founder wants to register "株式会社NovaTech" in Japan. The checker confirms the name is technically compliant for registration. However, it notes that trademark protection in Japan requires a separate filing under the Trademark Act — registration of the company name does not confer trademark rights.
Q: Can I use a name that is very similar to (but not identical to) an existing famous company?
A: Registration may succeed because the same-name-same-address rule is narrow. However, you would face significant legal risk under Article 8 of the Companies Act and the Unfair Competition Prevention Act. The checker flags potentially misleading names, but a full trademark and competition law analysis requires professional advice.
Q: What if I want to change my company name after formation?
A: A name change requires an amendment to the articles of incorporation (by special resolution), followed by a change registration at the Legal Affairs Bureau with a ¥30,000 registration tax.
Q: Do the naming rules differ for different entity types?
A: The character restrictions and prohibited term rules apply equally to all entity types. The only difference is which entity designation must be included (株式会社, 合同会社, etc.).
Check your proposed name against every applicable naming rule:
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Your name is compliant. Your entity is chosen. MmowW Scribe takes you through every remaining formation step.
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