A power supply system for a vehicle is provided with a battery (10), a plurality of charging paths (43, 53) for charging the battery (10) with external power, a plurality of relays (51-1, 51-2) disposed on the respective charging paths and for switching between supplying power and cutting power, and a charging control unit (46) for selecting, on the basis of the welding state of the plurality of relays, a charging path from among the charging paths which would be allowed to charge the battery.