PURPOSE: To bring the IC circuit to a correct connecting state with an external circuit by providing a transistor switching circuit and controlling the protective circuit so that pins at the positions of a symmetrical point are replaced mutually in response to the polarity of supply voltage at a maximum potential supply pin and a minimum potential supply pin and connected to the IC circuit.

CONSTITUTION: When supply voltage applied from a printed substrate, etc. is +VS and -VS on mounting, applied voltage of two kinds is applied to supply pins 16, 8 in response to the direction of a package. When the package is directed to A, -VS is applied to the gates of transistors Q1, Q3, and +VS is applied to the gates of transistors Q2, Q4. Since the transistors Q1, Q2 represent P channel transistors and the transistors Q3, Q4 N channel transistors, however, the transistors Q1, Q4 are turned ON and the transistors Q2, Q3 are turned OFF, +VS is applied to the supply terminal V+ of an IC circuit proper C and -VS to a supply terminal V- respectively, and the IC circuit is brought to a normal connecting state.