An irregular voltage detection and cutoff circuit using a bandgap reference voltage generation circuit includes the bandgap reference voltage generation circuit, which generates a bandgap reference voltage from the power-supply voltage, a reference voltage generator, which generates a first reference voltage and a second reference voltage in the same voltage level as the bandgap reference voltage from the power-supply voltage, a voltage detector, which generates a detection voltage from the power-supply voltage, and a comparator, which generates a switching control signal that cuts off the power-supply voltage by comparing the first and second reference voltages with the detection voltage.