民法第612条
Restriction on Assignment of Leasehold Rights and Sublease
賃借権の譲渡及び転貸の制限
Plain-language explanation
Article 612 of the Civil Code governs what a tenant can and cannot do with a leased property regarding third parties. Paragraph 1 states that a tenant cannot assign their leasehold right to someone else, nor sublease the rented property, without first obtaining the landlord's consent. This protects the landlord's legitimate interest in knowing and approving who actually occupies or uses their property, since an unauthorized occupant could pose risks (damage, non-payment, misuse) that the landlord never agreed to accept.
Paragraph 2 provides the consequence for violating this rule: if a tenant lets a third party use or benefit from the property without the landlord's consent, the landlord may terminate (cancel) the lease agreement. In practice, Japanese courts apply a "breach of trust" doctrine — minor, harmless unauthorized use (like letting a family member stay temporarily) may not be serious enough to justify termination, but clear unauthorized subleasing or business transfers to strangers typically will be.
This article is highly relevant in commercial real estate, office leases, retail store leases, and residential apartment rentals. Businesses expanding, restructuring, or bringing in partners often need to sublease space or transfer lease rights — doing so without landlord approval risks eviction and contract termination. Well-drafted lease agreements typically include explicit clauses requiring written landlord consent for any assignment or sublease, and clearly define the consent process to avoid disputes.
日本語での解説
民法第612条は、賃貸借契約において賃借人が勝手に第三者へ物件を貸したり、賃借権を譲り渡したりすることを禁止するルールです。第1項では、賃借人が自分の賃借権を他人に譲渡したり、借りている物件を転貸(また貸し)したりする場合には、必ず賃貸人(大家・オーナー)の承諾を得なければならないと定めています。これは、賃貸人にとって「誰に物件を使わせるか」は重要な利害関係であり、無断で見知らぬ第三者に使わせられると困るためです。
第2項では、もし賃借人がこの承諾を得ずに勝手に第三者へ使用させた場合、賃貸人はその賃貸借契約を解除できると定めています。つまり、無断転貸・無断譲渡は契約違反であり、最悪の場合は契約を打ち切られ、物件から退去を求められるリスクがあるということです。ただし判例上、信頼関係が破壊されない程度の軽微な無断使用(例:家族に一時的に使わせる等)では解除が認められないこともあり、実務上は「信頼関係破壊の法理」が重要な判断基準となります。
ビジネスの現場では、オフィス・店舗・工場・アパートなど様々な賃貸借契約でこの条文が問題になります。契約書に「転貸禁止」「譲渡禁止」の特約を明記し、承諾を得る手続き(書面での事前承諾など)を定めておくことが、トラブル防止の実務上のポイントです。
Common scenarios
- ▸A tenant company wants to sublease part of its office space to another business without asking the landlord
- ▸A retail tenant sells its business and tries to transfer the store lease to the new owner without landlord approval
- ▸An apartment tenant lets a friend or relative move in and effectively occupy the unit long-term without notifying the landlord
- ▸A franchisee wants to bring in a new operating partner to run the leased premises
- ▸A company restructures and tries to transfer its factory lease to a subsidiary without the landlord's consent
Related statutes
- 民法第613条
- 民法第616条
- 民法第541条
- 借地借家法第31条
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