An electric powered vehicle is equipped with a main battery for storing electric power input to and output from a motor, and an auxiliary battery as a power source for an auxiliary system including a control system. A DC/DC converter converts an output voltage of the main battery to a level of an output voltage of the auxiliary battery. During operation, a BAT-ECU monitors states of charge of the main battery and the auxiliary battery and controls operation/stop of the DC/DC converter. When the electric powered vehicle is in a key-off state (running stop state), the BAT-ECU is intermittently operated, while an external charging system and a vehicle running system are stopped.