In a power supply system, a controller is electrically connected with a plurality of switching elements of a multiphase inverter. The controller switches the plurality of switching elements on and off during a multiphase motor being activated. This converts a voltage of a first power storage device into a multiphase AC voltage so as to supply the multiphase AC voltage to the multiphase motor. This also boosts a voltage of a second power storage device to charge the first power storage device by the boosted voltage via multiphase windings of the motor. The controller switches the plurality of switching elements on and off during the multiphase motor being inactivated to thereby boost the voltage of the second power storage device to charge the first power storage device by the boosted voltage.