To rapidly and easily cover a pipe holding part in one operation by piercing a pin-like stopper having a plurality of expandable spring pieces in an insertion hole of a connection piece formed in both end parts of the opening/closing pipe bolding part.

After a pipe is fitted into a holding part 100, an insertion hole 121 of a connection piece 120 is fitted to a piercing part of a stopper 300. Though a spring piece 322 of the stopper 300 is contracted when passing through the insertion hole 121, it is expanded by the spring force after passing, and the stopper 300 is surely prevented from coming off to a bead part 312 side. The holding part 100 is formed in an opening/closing manner in accordance with the shape of the outer circumference of the pipe, and insertion holes 111, 121 in the stopper 300 air bored in a pair of connection pieces 110, 120 which are continuously provided on a free end part. The stopper 300 comprises a pin body 310 and a cylindrical body 320 fitted to the outer circumference of a shaft part 311, a cut 321 is formed in the outer circumference of the cylindrical body 320, and an expandable spring piece 322 is arranged.