A tube joint comprising: a nipple configured to be inserted in a tube body having flexibility, the nipple being provided to be opposed to an inner surface of the tube body; a clamping member having a tapered surface provided to be opposed to an outer periphery of the nipple and provided so that a diameter thereof gradually becomes larger in an inserting direction of the tube body; a sleeve provided to be movable to and fro along the tapered surface in an inclined direction of the tapered surface, and which elastically and radially expands or contracts in a radial direction; and an elastic member provided so as to push the sleeve along the tapered surface in a direction opposite to the inserting direction of the tube body, wherein the sleeve includes: a projection part configured to be formed in an inner periphery of the sleeve so as to protrude with respect to the outer periphery of the nipple, and configured to be disposed to butt against a tip surface of the tube body opposed to the inserting direction of the tube body when inserting the tube body, and to be disposed so as to radially contract with respect to an outer surface of the tube body when moving in the direction opposite to the inserting direction of the tube body; and a sliding surface configured to be formed on an outer periphery of the sleeve to be opposed to the tapered surface, and to move along the tapered surface in the inserting direction of the tube body when the projection part butts against the tip surface of the tube body, and to be disposed so as to move in the direction opposite to the inserting direction of the tube body due to the elastic member, a nd wherein the projection part radially expands so that the tip surface of the tube body comes off the projection part by being moved in the inserting direction of the tube body when butting against the tip surface of the tube body, and the projection part radially contracts so as to be smaller than an external diameter of the tube body when moving in the direction opposite to the inserting direction of the tube body due to the elastic member, wherein the nipple includes an annular seal member configured to be fixed to an annular recessed part formed in the outer periphery of the nipple, and to protrude in the radial direction; wherein a rib part is provided to the outer periphery of the nipple so as to protrude gradually with respect to the outer peripheral edge (1c1) of the annular seal member, characterized in that a plurality of the rib parts is dispersedly disposed along the outer periphery in the circumferential direction closer to a tip end of the nipple than at least the annular seal member. a nipple configured to be inserted in a tube body having flexibility, the nipple being provided to be opposed to an inner surface of the tube body; a clamping member having a tapered surface provided to be opposed to an outer periphery of the nipple and provided so that a diameter thereof gradually becomes larger in an inserting direction of the tube body; a sleeve provided to be movable to and fro along the tapered surface in an inclined direction of the tapered surface, and which elastically and radially expands or contracts in a radial direction; and an elastic member provided so as to push the sleeve along the tapered surface in a direction opposite to the inserting direction of the tube body, a projection part configured to be formed in an inner periphery of the sleeve so as to protrude with respect to the outer periphery of the nipple, and configured to be disposed to butt against a tip surface of the tube body opposed to the inserting direction of the tube body when inserting the tube body, and to be disposed so as to radially contract with respect to an outer surface of the tube body when moving in the direction opposite to the inserting direction of the tube body; and a sliding surface configured to be formed on an outer periphery of the sleeve to be opposed to the tapered surface, and to move along the tapered surface in the inserting direction of the tube body when the projection part butts against the tip surface of the tube body, and to be disposed so as to move in the direction opposite to the inserting direction of the tube body due to the elastic member, a nd wherein the projection part radially expands so that the tip surface of the tube body comes off the projection part by being moved in the inserting direction of the tube body when butting against the tip surface of the tube body, and the projection part radially contracts so as to be smaller than an external diameter of the tube body when moving in the direction opposite to the inserting direction of the tube body due to the elastic member, wherein the nipple includes an annular seal member configured to be fixed to an annular recessed part formed in the outer periphery of the nipple, and to protrude in the radial direction; wherein a rib part is provided to the outer periphery of the nipple so as to protrude gradually with respect to the outer peripheral edge (1c1) of the annular seal member, characterized in that a plurality of the rib parts is dispersedly disposed along the outer periphery in the circumferential direction closer to a tip end of the nipple than at least the annular seal member.