Acquisition unit 184 acquires an adjustment period in which power supply and demand is adjusted, and adjustment power which is power to be adjusted in the adjustment period. Adjustment target determining unit 185 requests an adjustment target storage battery to be charged or discharged at a predetermined electricity rate in the adjustment period and determines, based on the adjustment power, adjustment target storage batteries from among the storage batteries that have responded to the request. In the adjustment period, control unit 186 causes the adjustment target storage batteries to charge or discharge electricity at the predetermined electricity rate and causes a non-adjusted storage battery that is different from the adjustment target storage battery to charge or discharge electricity at an electricity rate different from the predetermined electricity rate.