A current-restriction circuit includes an input terminal to which an input voltage is input, an output terminal from which an output voltage is output, a driver transistor connected to the input terminal as well as the output terminal, a sense transistor connected to the output terminal as well as the input terminal via a sense resistor, a first operational amplifier circuit, and a bias-voltage change circuit. Control terminals of the driver transistor and the sense transistor are connected together and connected to an output terminal of the first operational amplifier circuit. The first operational amplifier circuit receives both a bias voltage with reference to an electrical potential at the input terminal and a decrease in a voltage at the sense resistor. The bias-voltage change circuit keeps the bias voltage below a predetermined bias voltage according to a voltage difference between the input voltage and the output voltage.