To provide an intermediate method for power supply, capable of performing power supply between a specific power supplier and a specific power user.

A system server 7 receives a power supply request for supplying at least a part of power generated by the power supplier 1 to the specific power user 3 through communication. During a prescribed period, power supplier electric power used information of the power supplier 1 are acquired from an A- power company terminal of an A-power company 2, to which the power supplier 1 belongs and power user power used information of the power user 3 are acquired from a B-power company terminal 12 of a B-power company 4, to which a power user 3 belongs through communication. On the basis of the acquired information on power supplier electric power used and information on power user electric power used, power supplier compensated electric power as the actual power used of the power supplier 1 and the power user compensated power which is the actual power used of the power user 3 are calculated.