To automatically measure pump characteristics without stopping operation of a water treatment plant facility.

A control device 10 monitors whether a pumping amount q and an average rotation speed n of suction pumps P1-PN are within prescribed ranges, and then detects average water level differences h1-h13 when the pumping amount q and the average rotation speed n of the suction pumps P1-PN are within the prescribed ranges. The control device 10 stores the detected average water level differences h1-h13, and pumping amounts q1-q5 and average rotation speeds n1-n3 of corresponding suction pumps P1-P3 in association with each other, and calculates a Q-H curve and a load curve of the suction pumps P1-PN by using the associated and stored average water level differences h1-h13 and the pumping amounts q1-q5 of the suction pumps P1-PN and the average rotation speeds n1-n3 of the suction pumps P1-PN.