PURPOSE: To feed stably the gate power supplies for the switching elements of an inverter device, by performing the ON-OFF control of a DC circuit power supply which is related to the feeds of the gate power supplies of the positive and negative side switching elements of the inverter section of the inverter device wherein a DC power is converted into an AC power.

CONSTITUTION: To the input of a photo-coupler PCX, a controlling signal gxa for a switching element SX is inputted, and the driving of the switching element SX is controlled by the output of the photo-coupler PCX via a gate resistor Rgx. In the controlling section of the switching elements, a starting signal ST for the control of an inverter device is inputted to a monostable circuit 14, and the starting signal ST is outputted from the monostable circuit 14 during a fixed term determined by the setting of the monostable circuit 14. Then, to an OR circuit 15, the output signal of the monostable circuit 14 and a controlling signal gx for the switching element SX are inputted, and the output signal gxa of the OR circuit 15 is used as the new controlling signal for the switching element SX. In case of the starting of the inverter device, the switching element SX is forced to be in ON-state during the fixed term, and a switching element SU is forced to be in OFF-state during the fixed term. Thereby, the gate power supply for the switching element SU is established.