To provide an operation control system and method for a pump that can offer a slow stop even upon a service interruption and can reduce the size and weight of a pump.

The operation control system for a pump comprises a battery 17 as an auxiliary power source connected to a converter circuit 10 and an inverter circuit 11, and a service interruption detecting circuit 16 for detecting a shutoff of power supply from an AC power source 7. In a normal operation of a pump 3, the battery 17 is charged up with DC power supplied from the converter circuit 10. If the service interruption detecting circuit 16 detects a shutoff of power supply from the AC power source 7, the battery 17 supplies the DC power to the inverter circuit 11, whose control circuit 12 then drives the inverter circuit 11 so that the frequency of AC power supplied to an AC motor 3c is gradually reduced to provide a slow stop of the pump.