An A.C. generator has a rotor that is equipped with a permanent magnet and a field coil. The output of the A.C. generator charges the high-voltage battery. Voltage of the high-voltage battery is stepped-down by a DC/DC converter and supplied to the low-voltage battery. When the motor controller detects that the field coil has not been energized, the higher-rank controller switches so as to generate power by means of the permanent magnet of the A.C. generator and charge the low-voltage battery. This mechanism enables power to be generated when a circuit malfunctions.Thereby, a power supply system for vehicle can generate power when a circuit malfunctions so that the driver on the vehicle can drive the vehicle to a repair shop.