To reduce costs and improve efficiency by providing the control circuit of first to fourth switching elements between a first output node and a common node and between a second output node and the common node.

A first stabilization circuit 106 is connected to a first end part X1 of secondary side transformer coil winding XFRMR, and a stabilization output voltage Vout1 is generated between an output node 108 and ground 110. Also, a second stabilization circuit 112 is connected to a second end part X2, and a stabilization output voltage Vout2 is generated between an output node 114 and the ground 110. Then, a control circuit generates a drive signal for transistors Q1 and Q3 so that the transition of the ON edge of the voltage pulse of a drive signal from the second partial cycle of an AC voltage to a first partial cycle essentially coincides with the transition from the first partial cycle to the second partial cycle, thus reducing costs and at the same time improving efficiency.