A shunt regulator includes: a capacitor, connected between an output terminal and a ground terminal; a voltage divider circuit and an output transistor, connected between the output terminal and the ground terminal; an error amplifier, controlling the output transistor based on a voltage at an output terminal of the voltage divider circuit and a reference voltage; a non-volatile memory; a memory control circuit, outputting a data read signal to the non-volatile memory; and a voltage detection circuit, detecting that a voltage at the output terminal has reached a predetermined voltage which permits a data reading operation of the non-volatile memory, and outputting a detection signal to the memory control circuit. An operating current of the non-volatile memory is supplied from the capacitor.