To provide a technique which decreases occurrence frequency of a state in which electric power is used more than targeted value of used power per one demand time.

A demand controller comprises a peak time prediction unit, a consumption power prediction unit and a power control unit 38. The peak time prediction unit refers to a database 30 to obtain a peak time of power consumption consumed by a power consumption apparatus. The consumption power prediction unit refers to the database 30 to obtain a prediction value of power consumption consumed by the power consumption apparatus in each demand time existed between the start of the demand time and the peak time predicted by the peak time prediction unit. The power control unit 38 supplies power from a secondary battery 10 to the power consumption apparatus, when the prediction value of power consumption from start to finish of the demand time is more than a targeted value of power consumption for the demand time, and when the sum of each difference between the prediction value of power consumption in each demand time existed between the start of the demand time and the peak time predicted by the consumption power prediction unit and the targeted value of power consumption is less than residual charging capacity of the secondary battery 10.