PURPOSE: To suppress the rapid increase of a water level even when any abnormality such as a heavy rain is generated by starting a pump before the water level reaches the water level to start the pump when the water level is considerably increased.

CONSTITUTION: When the water level is rapidly increased and reaches a first pump equipment stop water level L3, an abnormal timer still counts time. When the abnormal timer stops counting earlier than a normal timer in such a state, a forced relay is energized a forced contact T1X 15 closed, a relay RH1 is energized and a first pump P1 is started. Namely, when time for increasing the water level from a second pump stop water level L2 to the water level L3 is shorter than normal time, the pump P1 is started and the degree of water level increase is reduced before the water level reaches a first pump operation water level H1. Similarly, pumps P2 and P3 are started as well. Thus, in the process of abnormally increasing the water level, respective pumps P1,P2 and P3 corresponding to the water level are started before the water level reaches respective first, second and third pump operation water levels H1, H2 and H3 set at the time of normal increase.