The VCC detecting circuit 108 is composed of resistors 161 and 162 that divides the voltage VCC, an operational amplifier 163 that uses the boosted voltage VINT to compare the reference voltage VREF with a voltage obtained as a result of the dividing by the resistors 161 and 162, an NMOS transistor 164 that switches a current source in the operational amplifier 163, an inverter circuit 165 which u