To realize a resistor for preventing and suppressing rush current and a discharge resistor with a single resistor.

A source side arm including a thyristor Q1 and a sink side arm including a thyristor Q2 are further provided at a single-layer full-wave rectification bridge which is constituted of diodes D1-D4. A transistor Q3 is provided in parallel with the diode D1 and a thyristor Q4 is provided in parallel with the thyristor Q2 and a resistor R is provided between the connection point of the diodes D1 and D2 and the connection point of the thyristors Q1 and Q2. To charge up a capacitance load C using the output of an AC power supply 10, the thyristors Q1 and Q2 and the transistors Q3 and Q4 are turned off, thus inserting the resistor R into a charging path. When charging down the capacitance load C, the transistors Q3 and Q4 are turned on, thus inserting the resistor R into the discharge path of the capacitance load C.