PROBLEM TO BE SOLVED: To cut contract demand without increasing battery capacity, by dividing load inside premises into a specific number of systems, normally feeding the load of the first system, feeding the load of the second system from a battery only at power peak time, and stopping feeding the load of the third system only at power peak time. SOLUTION: Divided into three systems, DC loads 3a to 3c, loads inside premises, are connected parallel to a rectifier 2. The first load 3a is normally fed from an AC power supply 1 via the rectifier 2, the second load 3b is fed from a battery 6 only at power peak time, and the feeding of the third load 3c is stopped only at the power peak time. With this structure, peak shift can be performed by supplying DC power at the power peak time to the second load from the battery 6 which had been charged at the time of low power rates. This peak shift combined with the simultaneous peak-cut by stopping feeding the third load 3c can cut contract demand without increasing the capacity of the battery 6.