Reason for cancellation

...To terminate a contract that was once valid, and to extinguish it after the fact. In a contract that contains a continuing legal relationship, such as a lease contract, if the duration of the contract is not specified, both parties have the authority to terminate the contract at any time, and if the other party to the contract defaults on the obligation or there is some other specific reason (cause for termination), the other party has the authority to terminate the contract (termination right), and the contract is dissolved in the future by the expression of intention to terminate by the person with the right to terminate. In everyday language, "termination" and "cancellation" are often not distinguished as both are used to terminate a contract, but legally the two are distinguished.

*Some of the terminology explanations that refer to "causes for termination" are listed below.

Source | Heibonsha World Encyclopedia 2nd Edition | Information

…解除とともに，いったんは有効に成立した契約を事後的に消滅させること。賃貸借契約のような継続的な法律関係を内容とする契約において，契約の存続期間の定めがないときには，いつでも両当事者に，また契約の相手方に債務不履行その他一定の事由(解約原因)があるときには，もう一方の当事者に契約を解約する権限(解約権)が発生し，解約権者の解約の意思表示によって契約は将来に向かって解消される。日常用語では〈解除〉と〈解約〉とは，ともに契約を解消させるものとして区別されないことが多いが，法律上は両者は区別される。…

※「解約原因」について言及している用語解説の一部を掲載しています。

出典｜株式会社平凡社世界大百科事典 第２版について | 情報