To suppress the lowering of performance of a submerged pump 1 even while avoiding clogging in a pipe line when a passage particle size of the pipe line disposed on the downstream side of the submerged pump 1 is smaller than a passage particle size of the submerged pump 1.

In a suction port 4 disposed on a casing 22, a passage particle size thereof is set to d, and the passage particle size is the smallest passage particle size in a pump part 2. Furthermore, the suction port is formed in such a shape that at least one opening edge E exists in a range C of a radius d/2 with an arbitrary point within an opening thereof as a center P and an opening area of the suction port is set to be larger than πd²/4.