By previously press-fitting a ring (40) into one end portion (12) of a tube (11), the one end portion (12) is held in the flared state. With an inner cylindrical portion (22) of the joint main body (20) having been inserted into this ring (40) while the one end portion (12) having been press-fitted into a recessed groove (21) to the innermost recess portion, a greatest wall thickness portion (41) of the ring is covered. In this state, with a cap nut (30) being screwed with the joint main body (20), the greatest wall thickness portion (41) of the ring is pressed against the inner cylindrical portion (22) together with the one end portion (12) through an outer cylindrical portion (23), and a hole peripheral edge (34a) of an insertion hole (34) of the cap nut is pressure-contacted with a bent portion (12c) of the tube by the ring (40).