To provide a method for detecting closing anomaly of the suction valve and opening anomaly of the discharge valve of a pump as the anomaly of a filter press having an air-driven double diaphragm pump as a slurry feed pump.

In the anomaly detection method of the filter press including the air-driven double diaphragm pump as a slurry feed pump, the time required for one feeding of the slurry is sequentially measured. When a square (T1/T2)2 of a ratio of T1/T2 of the current feeding time T1 to the previous feeding time T2 is equal to or less than a first prescribed value which is less than 1, the suction valve of the pump is determined to have caused closing failure, and when (T1/T2)2 is equal to or less than a second prescribed value which is less than 2, the discharge valve of the pump is determined to have caused opening failure.