To provide an anticlogging device for a pumping well of a pumping system used for earth retaining excavation works.

The pumping system constructs an earth retaining wall 10 in the ground and is used in an earth retaining excavation work excavating the inside of the earth retaining wall 10 up to the predetermined depth, In this time, a pumping well 12 is provided at the internal side of the earth retaining wall 10 for collecting drain water W1 including water generated from construction works, rainwater, underground water, etc. Further, a condensating well 14 is provided at the external side of the earth retaining wall 10. Drain water W1 collected in the pumping well 12 is pumped up to feed it into the condensating well 14 and returned to the underground water stream through a filter layer 14b. In the circuit in which the drain water W1 is fed in the condensating well 14, an anticlogging device 20 separately removing foreign materials such as sand soil in the drain water W1 onto the ground is installed.