To provide a constant voltage output circuit for stabilizing an output at the time of the fluctuation of power supply voltage.

This constant voltage output circuit comprises a differential amplifier circuit in which a first input terminal is connected to reference voltage, an output transistor in which a source terminal is connected to the power supply voltage, a drain terminal is connected to an output terminal and a gate terminal is connected to the output terminal of the differential amplifier circuit, a first resistance element in which one end is connected to the output terminal and the other end is connected to a second input terminal of the differential amplifier circuit, a second resistance element in which one end is connected to the first resistance element and the second input terminal of the differential amplifier circuit and the other end is grounded, and a capacitive element in which one end is connected to the power supply voltage and the other end is connected to the output terminal of the differential amplifier circuit.