To conduct a charge by a lower energy charge in a consumer's house charging a battery for an electric vehicle.

A communication repeater 4 connecting the electric vehicle 2 and a power server 3 in a communicable manner is installed in the consumer's house H. Databases 31 and 32 storing information containing the energy charges at every time zone by the contract contents of energy charge menus contracted by each consumer's house H and databases 33 and 34 storing charging characteristics of each battery are installed in the power server 3. When receiving a charging completion appointed time and the discriminating information of the consumer's house H from the electric vehicle 2 side through the communication repeater 4, a charging start time is computed so that the charge is completed up to the charge completion appointed time and the energy charge required for the charge is lowered on the basis of the contract contents contracted by the consumer's house H.

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