A power supply device for controlling power supply from a power supply source to loads, comprising: a power storage element; a first circuit that connects the power supply source and the power storage element so as to be chargeable; a second circuit that connects the power storage element and the loads so as to be dischargeable; a third circuit that connects the power supply source and the loads so as to be able to supply power; and a control unit that controls the first circuit so as to charge the power storage element with the power of the power supply source when a predetermined signal is detected, and controls the third circuit so as to supply the power of the power supply source to the loads.