PURPOSE: To make most of the merit of save-power drive by switching the emitter follower circuit into the cut-off state in interlocking with the ON-OFF of a gate drive signal.

CONSTITUTION: An N-channel MOSFET1, a gate drive circuit 2, a PNP transistor(TR) 3 whose emitter and collector are connected respectively between the gate and source of the MOSFET1, and a base current supply resistor 4 connected between the collector and base of the TR 3 constitute an emitter follower circuit. Then a diode 5 connected between the base and emitter of the TR 3 switches the emitter follower circuit into the operating state or the cut-off state by using a gate drive signal from the base of the TR 3. Thus, the resistance between the gate and source of the MOSFET1 is kept to a low resistance in the OFF-state and the power consumption of the gate-drive circuit 2 is reduced. Thus, the merit of the power-saving drive is sufficiently utilized.