A semiconductor device for control applied to a constant-voltage power supply device includes a digital-analog converter circuit which outputs a reference voltage corresponding to a value of a first register with taking an output voltage of a reference voltage source as a criterial reference voltage, and generates a control signal for driving a power semiconductor device based on an output voltage of an error amplifier which differentially amplifies a feedback voltage obtained by resistive-dividing on an output voltage of the constant-voltage power supply device and the reference voltage. An analog-digital converter circuit which converts the feedback voltage to a digital value with taking the output voltage of the constant-voltage power supply device as a reference voltage is provided, and based on the output, a value of a first register is corrected so as to offset an effect of an error in voltage dividing ratio of a voltage dividing resistor circuit.