Abstract: In a Bi-CMOS output circuit constituted by combining a bipolar transistor and a CMOS circuit, in an output circuit obtained by connecting current paths of two bipolar transistors in series between a power source and ground, when the bipolar transistor connected to ground is driven by a bipolar transistor, an output current value can be assured when an output voltage is low. However, when the output voltage is high, a large current is supplied to the bipolar transistor to vary a power source voltage. Therefore, the output terminal of the MOS transistor is connected through a resistor to the grounded control signal input terminal of the bipolar transistor. Since the bipolar transistor connected to the ground is driven by a MOS transistor having drivability lower than that of a normal bipolar transistor, when the output voltage is low, a predetermined current can be assured. When the output voltage is high, supply of a large current can be prevented.