A band-gap type constant voltage generating circuit is produced in a semiconductor chip, and has a first potential terminal and a second potential terminal. A band-gap circuit includes first and second transistors having respective bases connected to each other, a first resistor connected between emitters of the first and second transistors, and a second resistor connected between the emitter of the second transistor and the first potential terminal. A constant voltage production circuit is provided between the first and second potential terminals to produce and output a constant voltage based on a base-emitter voltage of the second transistor of the band-gap circuit, and the constant voltage is fed as a feedback signal to the base of the second transistor of the band-gap circuit. A driver circuit is provided between the first and second potential terminals and connected to collectors of the first and second transistors to drive the band-gap circuit. The driver circuit is constituted such that an influence of absolute process fluctuation, to which the semiconductor chip is subjected during a production process thereof, is eliminated from the constant voltage.