Battery state of charge transfer device and an external charging system

A communication part (41) of a battery state of charge transfer device (4) a loading device (3) is obtained state of charge information of each external charge vehicle (1). A communication station (42) transfers the charge status information to an information management station apparatus (5). The charge state information is grouped for transmission, so that the number of transmissions, the communication traffic volume and the cost of communication with the management station device (5) and the operating load of the management station device (5) be reduced.