A drive circuit for a switching circuit has a high-side drive circuit to turn on/off, according to a control signal, a switching element QH arranged on a high side of a DC power source Vin and a low-side drive circuit to turn on/off alternately with the switching element QH according to the control signal a switching element QL arranged on a low side of the DC power source and connected in series with the switching element QH. Ends of an auxiliary power source Vcc1 are connected in series with a switch element Qn1, a capacitor C1, and a switch element Qn2. Both ends of the capacitor C1 are connected in series with a switch element Qp1, a capacitor C2, and a switch element Qp2. A control circuit alternately turns on/off the switch elements Qn1 and Qn2 and the switch elements Qp1 and Qp2. The capacitor C2 provides the high-side drive circuit with source power.