PURPOSE: To increase the electrostatic breakdown strength of an output by making the depth of a base in an emitter-follower-transistor connected to an output terminal deeper than that of a base in a transistor for switching in an internal circuit.

CONSTITUTION: The depth of a base region in an emitter-follower-transistor is formed in size deeper than that of a base region in a transistor for switching in an internal circuit. That is, the depth tBIO, tBIS of each base region 4, 4' in an output transistor and the switching transistor differs, but the depth of respective emitter region 5 is equalized. The depth tBIO of the base region 4 of the output transistor is brought to a value such as 0.5μm and the depth tBIS of the base region 4' of the switching transistor to 0.3μm and the depth tEIO, tEIS of each emitter region 5 of these transistors is brought to 0.1μm. Accordingly, the electrostatic breakdown strength of an output terminal can be increased without deteriorating the performance of an IC.