An electric power storage system for a vehicle includes: an electric power storage device; a converter configured to perform voltage conversion between the device and the motor; a DC/DC converter configured to step down an output voltage to an auxiliary machine or an auxiliary machine battery; a charger configured to charge the device with external electric power; and first and second relays disposed on first and second connection lines connecting the device to the converter, respectively. One end of the DC/DC converter is connected to the first connection line between the first relay and the converter and the other end is connected to the second connection line between the device and the second relay. The charger is disposed on a current path capable of charging the device with the external electric power when the first relay is in an ON state and the second relay is in an OFF state.