To cut the peak of a total water distribution volume by executing fuzzy inference based on the water level of a water tank in a specified water distributing area and a present water distribution volume and controlling the water distribution volume in at least one specified water distributing area among plural water distributing areas.

In the fuzzy operation part 80 of a water distribution control part 50, the water reception start level of the water tank 43, namely, the open water level of a water reception valve 42 and the water reception stop level of the water tank 43, namely, the close water level of the water reception valve 42 are fuzzily inferred from the present total water distribution volume and the increase/decrease tendency of the water distribution volume. The peak of the total water distribution volume and a water reception period are shifted, and the water level effective for peak cut is set. The fuzzy operation part 80 executes an operation with respective membership functions based on a prescribed fuzzy rule, corrects valve open/close water levels and executes fuzzy inference. When the water distribution volume is large and the change of the water distribution volume increases, the open water level is dropped. Thus, the peak of the total water distribution volume can be suppressed.