PURPOSE:To stabilize an action and enhance reliability, by transferring the ON-signal of the switching element of voltage different from that of an oscillation circuit with the flow of current, via no insulating element, when the switching element on the side of the same potential as that of the oscillation circuit is off. CONSTITUTION:By an inverter, to both the ends of a DC power source V, the series circuit of switching elements Q1, Q2 is connected, and by the output V1, V2 of drive circuits 1, 2, the circuit is driven on/off. To both the ends of the one side element Q2, via a inductance Lo, a load Z and a capacitor Co are connected. The input of the signal VB of an oscillation circuit 3 to the drive circuit 1 via a signal transferring circuit consisting of transistors Tr1-Tr2 and the like is provided. In this case, by the signal VB' of the signal VB of the oscillation circuit 3 reversed at an inverter gate G1, the transistor Tr1 is driven. As a result, regenerative current from the load side to the power-supply side is reduced, and after that, current is conducted to a signal transferring passage, and stress applied to a circuit element is reduced.