When an overcurrent detection section detects an overcurrent, a control circuit performs ON-OFF control for switching devices each switchable between a forward direction and a reverse direction, in a mode in which a current having flowed is reduced, such that when the mode is a mode in which a current is passed through any of diodes, a switching device connected in parallel with the current-passed diode is turned ON. Thus, even when an overcurrent occurs, the current flowing in the diode connected in parallel with the switching device is reduced, and the diode is protected from being deteriorated or broken by the overcurrent.