To provide a pipe joint preventing easy loosening of a plug from a socket.

The joint includes the socket, and the plug 30 to be inserted and connected to the socket. The socket includes a socket body 10 having a first through-hole for a plug lock 12b and a long and slender second through-hole 13a for a sleeve operation element 50, and a sleeve 50 around the socket body. The sleeve presses the plug lock 12b against a lock recessed part of the plug and it is energized by a spring member 15 toward a position preventing loosening. The sleeve includes a lock face pressing against the plug lock in this position. When the plug is inserted into the socket, it engages with the sleeve operation element, thrusts back the sleeve, and facilitates loosening of the lock face from the plug lock.