To provide a protective circuit that suppresses thermal damage of a power supply circuit and suppresses damage due to heat generation of the power supply circuit, and provide a protective circuit and a power supply circuit with small occupied area and low manufacturing cost.

A semiconductor integrated circuit includes a voltage conversion circuit, and a control circuit having a voltage division circuit and a protective circuit. The protective circuit includes a first oxide semiconductor transistor whose off current increases as the temperature rises, a capacitor accumulating the off current as charges, a second oxide semiconductor transistor, and an operational amplifier whose non-inversion input terminal receives reference voltage. The first oxide semiconductor transistor is disposed adjacent to a heat generation element of the voltage conversion circuit or the control circuit.