A power supply apparatus includes, a power generating circuit that converts energy to power and output a voltage of the power, a first switch installed on either or both of a pair of power lines, a first switch control circuit that controls the first switch based on the level of the voltage, a second switch installed on a branched line coupled to the pair of power lines, a second switch control circuit that controls the second switch based on the level of the voltage, and controls the second switch so that the second switch is repeatedly turned on and off when a power storage circuit is charged with power generated by the power generating circuit, and the power storage circuit installed on the branched line and coupled to the power generating circuit when the first switch and the second switch are set to ON states.