The power supply apparatus includes a control unit that can perform intermittent operation of alternately repeating a switching period and a switching halt period, wherein the switching period is for performing switching operation of alternately turning on or turning off two switching elements across a turn-off period for turning off both of the two switching elements, and the switching halt period is for halting the switching operation. In a transition from the switching period to the switching halt period, the control unit makes the transition to the switching halt period after turning on a second switching element. In a transition from the switching halt period to the switching period, the control unit also makes the transition to the switching period after turning on the second switching element.