PURPOSE: To shorten an ON time while also reducing power consumption.

CONSTITUTION: Each collector of an N-P-N transistor 3 and a P-N-P transistor 4 is connected on the high potential side and low potential side of a DC power 8 respectively while bases are and also emitters are connected mutually, the bases are used as input terminals while the emitters are employed as output terminals, and the output terminals are connected to the gate of an electrostatic induction thyristor 9. The DC power 8 is voltage-divided by two series resistors 5, 6, a capacitor 7 is bonded in parallel with the resistor 6 on the low potential side while the high potential side of the node is connected to the cathode of the electrostatic induction thyristor 9, and a semiconductor switch 10 brought to an ON state only for the OFF period of the electrostatic induction thyristor 9 is bonded in series with the resistor 5 on the high potential side.