A resin pipe joint in which, although an economical configuration formed by two components or a joint body and a union nut is employed, both a resistance against pulling and an excellent sealing property can be attained is provided. A resin pipe joint is configured so that the joint has: a synthetic resin-made joint body 1 including an inner cylinder portion 4 and an external thread portion 5; and a synthetic resin-made union nut 2 including: an internal thread portion 8; a seal peripheral edge 10 which is actable on a tip-end portion of a tube flared portion 3A; a slipping-off prevention peripheral edge 11 which is actable on a large-diameter portion of the flaring changing region 9; and a pressing inner peripheral portion 13 which is externally fittable to a flared straight portion 12 that is fitted to a straight barrel cylinder portion 4B, and, by fastening of the union nut 2 in a state where an end of the tube 3 is inserted into the inner cylinder portion 4 and the flared portion 3A is formed, the pressing inner peripheral portion 13 is pressingly contacted with and externally fitted to the flared straight portion 12, a portion which is formed as a large-diameter portion of the flaring changing region 9 is pressed by the slipping-off prevention pressing portion 11, and a small-diameter portion of the flaring changing region 9 is pressed by the seal pressing portion 10.