PURPOSE: To provide a drive circuit, for a partial-resonance converter circuit, which is not affected by a change in the input voltage of a power supply and which can increase the efficiency of a switching operation.

CONSTITUTION: A drive circuit for a partial-resonance converter circuit synchronizes two switching elements (designated as switches in the following) S1, S2 so as to be operated. The drive circuit is provided with a control-signal generation circuit which contains a constant-voltage element Q1 and which generates a first control signal and a second control signal used to control the operation of the switches S1, S2 and with a pulse output circuit which outputs a first synchronizing pulse signal and a second synchronizing pulse signal having different pulse widths to the switches S1, S2 on the basis of the comparison result of the first and second control signals generated by the control-signal generation circuit with an identical reference signal wave. Then, the pulse output circuit outputs the first synchronizing pulse signal to the main switch S2, and it outputs the second synchronizing pulse signal to the switch S1.