To provide a plug for water conduction capable of preventing a filter from peeling or breaking.

A plug for water conduction includes a plug body 6a having a through hole 6d penetrating in an axial direction and a filter 7 provided in the through hole 6d and having water permeability. A filter protective member 8 having water permeability and a filter reinforcing member 10 having water permeability are provided in the through hole 7 with the filter 7 interposed, so even if earth/water pressure acts on the filter 7 from the ground side when a steel material is cast in the ground, the filter reinforcing member 10 suppresses the filter 7 from swelling. Therefore, the filter 7 is prevented from swelling to peel from the plug body or to break. Further, the filter 7 can be prevented from peeling or breaking similarly even if the ground is liquefied.