A power supply apparatus includes a storage battery and supplies a voltage from the battery to an electric load. The power supply apparatus includes first and second energizing paths connected in parallel between the battery and the load, a first switch making the first energizing path conductive and interrupting the first energizing path, and a second switch making the second energizing path conductive and interrupting the second energizing path. The power supply apparatus includes a first drive circuit that operates when a voltage is supplied and drives the first switch, a second drive circuit that operates when a voltage is supplied and drives the second switch into a conductive state in a case where the first switch is driven into a conductive state by the first drive circuit, first and second supply paths respectively supplying a voltage to the first and second drive circuits.