PURPOSE: To eliminate the need of special communication function on the charger side by connecting a vehicle-mounted battery and a charge controller with the charger in a charging stand having a charge controller through a connector there transmitting the state of battery.

CONSTITUTION: A battery 20 and a charge controller 30A are mounted on a vehicle. At the time of charging, a vehicle is moved to a charging stand equipped with a charger 70A where the connector of the vehicle is connected with the connector 100 of the charger and the connected state is detected through lines 51, 101. AC power fed through an insertion plug 98 is rectified 72 and fed through a constant current circuit 74 to the battery 20 which is thereby charged. The operating states of relays 36,76 at that time are fed, along with outputs from charge voltmeters 39, 79, charge ammeters 38, 78, temperature sensors 32, 82, and a leak sensor 84, to controllers 40, 90. The states of vehicle-mounted I/O processing circuits 40d, 40e are exchanged with the states of I/O processing circuits 90d, 90e on the charger side through the connectors 50, 100 and buses 4 44 and 92, 94. This circuitry allows positive charging without requiring any special communication unit.