A pipe joint includes: a joint main body with a receiving opening for a pipe; an axially-movable tube-shaped body mounted to the receiving opening; and a retaining ring closely arranged to an outer surface of the pipe for preventing the pipe from detaching, wherein the joint main body includes a receiving portion for receiving the retaining ring, and a tapered portion for radially shrinking the retaining ring, wherein the tube-shaped body is arranged to move between a first position where the retaining ring is allowed to move into the tapered portion, and a second position where the retaining ring is blocked from tapered portion, and wherein the pipe joint is configured such that the pipe can be inserted into the receiving opening when the tube-shaped body is either position, that in the first position the pipe is not detachable, and that in the second position the pipe is detachable.