A power supply apparatus includes an output terminal that supplies electric power, supplied from at least any of a plurality of power storage devices installed in a vehicle, to at least any of the plurality of pieces of equipment, and a switching part that switches whether respective connection terminals of the plurality of power storage devices are i) connected to one or more of connection terminals of other power storage devices among the plurality of power storage devices, ii) connected to the output terminals, or iii) not connected to any of terminals of the other power storage devices and the output terminals, and a switching controller that controls the switching part to cause the output terminal to output electric power supplied from at least any of the plurality of power storage devices.