To provide a cap, configured to facilitate the construction of the cap to a pipe member, and a pipe member with a cap.

The cap 2 attached to the opening end 14 of a pipe member 1 includes a lid 21 covering the opening end 14 of the pipe member 1, and an insert part 22 extended from the lid 21 and inserted into the pipe member 1. The insert part 22 is formed in an inclined shape relative to the lower end surface 23 of the lid 21 facing the opening end surface 16 of the pipe member 1. Then, a relative large gap can be provided between the outer wall surface of the insert part 22 and the inner wall surface of the pipe member 1 by inserting the insert part 22 of the cap in parallel to the longitudinal direction of the pipe material 1, and the inserting operation of the insert part 22 is facilitated.