To realize a partial resonance power switch which is provided with a pause time by preceding a power supply control signal, being fed to an auxiliary switch by a set time.

A resonance power switch, comprising a main switch Q1 and an auxiliary switch Q2 generating a switching power supply according to a power supply control pulse delivered from a PWM control section 12, is further provided a lead unit 14 generating a signal preceding the power supply control signal by a set time. The main switch Q1 is controlled by the power supply control signal, which the auxiliary switch Q2 is controlled by a signal delivered from the lead unit 14, such that the overlapped turn-on thereof is prevented by providing a pause time and the switches Q1, Q2 resonate between pause times.