To eliminate steps between contact faces and end faces of pipes to reduce flow resistance when the pipes different in thickness from each other are joined, by making thickness in a diametrical direction of a contact face of a socket differ from that of a contact face of another socket.

This pipe joint 1 made of hard vinyl chloride resin is provided with a socket 11 formed at one end of a pipe joint 1 and a socket 12 formed at another end thereof. A projecting portion 13 is projected and disposed at a central portion of an inner face of the pipe joint 1. A contact face 131 is disposed in the inner part of the socket 11, and a contact face 132 is disposed at that of the socket 12. Thickness L1 in a diametrical direction of the contact face 131 is formed to be larger than thickness L2 in a diametrical direction of the other contact face 132. By inserting a pipe, which is made of hard vinyl chloride resin and has thickness approximately equal to the thickness L1, into the faucet 11, and by inserting a pipe, which is made of hard vinyl chloride resin and has thickness approximately equal to the thickness L2, into the faucet 12, steps between each end face of the pipes and the contact faces 131, 132 of the pipe coupling 1 are eliminated. Therefore, flow resistance does not occur even when fluid flows through the joint portion of the pipes.