A switch circuit is comprised of first and second NPN transistors, the collectors of which are interconnected and the emitters of which are respectively connected to an input terminal and a reference voltage, third and fourth PNP transistors connected between the bases of said first and second transistors and a power source voltage, and fifth and sixth NPN transistors connected between the bases of the third and fourth transistors and ground. Seventh and eighth PNP transistors, connected between the power source and ground, are further provided, with their ON and OFF states being controlled by a control signal applied to the bases thereof. The bases of the fifth and sixth transistors are respectively connected to the collectors of the seventh and eighth transistors. The fifth and sixth transistors are ON/OFF controlled by the collector currents of the seventh and eighth transistors, respectively.