To facilitate separation of a socket and a plug from each other even when a bending load is applied.

This pipe coupling comprises a socket 2 having a sleeve 7 for operation operably fitted in the outer periphery of the tip part 5 of a socket body 4 between the lock position and the lock release position of a lock ball 6; and a plug 3 having a recessed part 10 which is formed in the tip part 9 of a plug body 8 and at which a protrusion part 82 and a ball 6 to move a ball 6 in a centrifugal direction during insertion of it in the tip part 5 and pull-off therefrom are locked. Through engagement and disengagement between the ball 6 and the recessed part 10, the socket 2 and the plug 3 are connected with or separated from each other. In this case, an annular packing 74 with which the forward end face of the plug body 8 makes contact is arranged at the deep part of the tip part 5 of the socket body 4. A gap is provided between the outer peripheral surface of the protrusion part 82 of the plug body 8 and the inner peripheral surface of the tip part 5. The recessed part 10 of the plug body 8 is extended long to a rear in an axial direction and a relief part 87 to avoid interference with the inner peripheral surface of the tip part 5 is arranged.