A power supply apparatus of the present invention has a power factor correction circuit that corrects a power factor; a voltage converter connected to a secondary side of the power factor correction circuit; a power control unit that outputs a first signal for turning the power factor correction circuit on, and outputs a second signal for turning the voltage converter on; and a signal output unit that, in accordance with having being inputted with the first signal and the second signal, outputs a signal for turning the voltage converter on.