To provide a piping joint structure capable of attaching a piping joint to the other member and having good sealability without requiring high processing accuracy for an attaching hole in a mating member.

This piping joint 10 comprises a joint body 11 constituted by a first parallel screw part 14 in which a straight one end part 13 can be screwed and attached into a parallel threaded hole 2 sequentially arranged from an end in the axial direction, a seal groove part 15 slightly recessed in the radial direction for the first parallel threaded part, and a second parallel threaded part 16, a seal ring 18 wound around the seal groove, and a lock nut 21 screwed into the second parallel screw part and provided with a storing recessed part 22 capable of storing the seal ring with the seal ring restrained against the end of the seal groove side. After the first parallel threaded part is screwed into the parallel threaded hole 2 formed perpendicular to a flat attaching surface 1a of a connection mating member 1, the piping joint is connected with the mating member fluid tightly with the seal ring pressed against the attaching surface by the lock nut.