The present invention provides a socket and a pipe joint which facilitate coupling and uncoupling of the socket and a plug and which can prevent the plug from jumping out of the socket in the uncoupling. In a socket 10 of the present invention, fluid in a built-in plug part 22 is released to the outside via communication holes 40 of a second base portion 18 and a through hole 51 of a third base portion 19 in a semi-inserted state. Accordingly, the pressure in a hole portion 34 does not become excessively high and an engaged part 42 is not unexpectedly pushed upward. Thus, an engagement portion 38 and a second engaged portion 26 can surely engage with each other. Hence, the plug 12 can be prevented from jumping out toward the front end side in the semi-inserted state.