Abstract: An air-pressure joint 1 comprising a pipe main body 2 made of a rigid thermoplastic resin and a release ring 3 made of a rigid thermoplastic resin inserted from one opening of the pipe main body, wherein the release ring includes a slip-off preventing protrusion 13 on an outer circumferential surface of its insertion site; and the pipe main body 2 includes a ring-shaped sealing portion 9 made of an elastic resin and integrally formed on an inner circumferential surface thereof, an insertion mouth pipe portion 7 made of a rigid rigid resin, coaxially disposed to abut one opening side portion of the pipe main body 2 and forming a recess groove 10 on an inner circumferential surface of an abutting portion thereof for stopping the slip-off preventing protrusion 13 of the release ring 3, and a ring-shaped connecting portion 8 made of a rigid synthetic resin and integrally molded to an outer circumferential surface of the abutting portion of this mouth pipe for connecting the insertion mouth pipe portion 7 to the p