When a vehicle is set to a travel control mode or external charging mode, a vehicle system is activated for executing the control mode to which the vehicle is set. A converter ECU selects one sub power storage unit to be used first after activation of the vehicle system, based on a power storage unit used after preceding activation as read from a memory unit contained in the converter ECU and based on respective states of charge of sub power storage units, and electrically connects the selected sub power storage unit and a converter via a switch circuit. When the vehicle system is activated for executing the travel control mode, the converter ECU updates information about the power storage unit used after preceding activation as stored in the memory unit, to information about the power storage unit used first after the present activation of the vehicle system. When the vehicle system has been activated for executing the external charging mode, the converter ECU maintains the information about power storage used after the preceding activation as stored in the memory.