PURPOSE: To permit the pumping of a great amount of underground water by a small-scale motor by the procedure in which the lower end of an endless belt made of cloth or urethane resin is dropped into the undergound water in a well and driven between a driving roll and a pressing idler while sequeezing out underground water absorbed in the belt.

CONSTITUTION: When dropping the lower end of an endless belt wound over a shaft 2 into the underground water in a well, the underground water is absorbed in the belt 1 made of a cloth or urethan resin. The thus-absorbed mater is then pressed and squeezed out by the spring 4 of the roller 3 when the belt 1 is driven. Then, the groundwater so squeezed out is discharged from the discharge port 14. Since the trailing half portion of the endless belt 1 is impregnated with water and the other belt portion thereof has already been pressed by the spring of the roller 3 and the underground water has already been squeezed out from the other half portion of the belt 1, the pumping of the underground water can be sufficiently only by a small-scale motor with only a power high enough to deive the belt 1. Also, even if the belt 1 can absorb a small amount of water, the pumping of great amounts of the water can be performed if its rotation speed is made faster.