To obtain a riser pipe which can efficiently prevent the diffusion of polluted soil by discharging groundwater in a polluted soil area from the polluted soil area, when the polluted soil exists in the area with a formed groundwater discharge hole.

This riser pipe comprises: a plurality of strainer connecting pipes which comprise a strainer connecting pipe body having joint connection portions formed in upper and lower parts, a plurality of slits formed in the strainer connecting pipe body and enabling the inflow of the groundwater, and a filtering net attached in such a manner as to cover an outer peripheral portion of the strainer connecting pipe body; a plurality of joints for linearly connecting the plurality of strainer connecting pipes together; and a well point which is attached to the leading-end strainer connecting pipe via the joint.