PURPOSE: To reduce power consumption and to reduce a chip area by connecting a capacitor between the gate of the MOSFET for gate shortcircuit of a bipolar transistor and the collector of the bipolar transistor. CONSTITUTION: When a transiently changing voltage is applied between the collector and the emitter, a displacement current flows between fixed potential V0 and the emitter electrode of an insulating gate bipolar transistor(IGBT) 1 via the capacitor 3 and the gate and source electrodes of the MOSFET 2 for gate short-circuit. The gate parasitic capacitances 8, 9 of the FET 2 are charged by the displacement current, which connects electrically the drain electrode to the source electrode. While, the parasitic capacitances 6, 7 of the IGBT are also charged. An electric charge which charges the parasitic capacitances is discharged via the FET 2. Therefore, the gate voltage of the IGBT is not increased, which excludes to turn, on the IGBT, and the displacement current flows only when the voltage changes. which reduces the power consumption.