A pipe joint comprising a cap nut and a joint body that itself includes an extraction preventing tooth part as an integral part that comes into a state of tightly contacting an outer peripheral surface of a connection target pipe (P) under pressure to generate pipe extraction resistance (Z) in response to threaded movement of the cap nut toward the joint body , wherein the extraction preventing tooth part is formed at a tip having a tip head of a substantially cylindrical thin part of a projecting shape provided at a tip of the joint body , the extraction preventing tooth part includes a back tooth and a front tooth arranged at a tiny interval (W 36 ), the back tooth has a trapezoidal or substantially trapezoidal sectional shape with a linear first tip side as an upper side, the front tooth has a trapezoidal or substantially trapezoidal sectional shape with a linear second tip side as an upper side, and as the cap nut threadedly moves forward, the first tip side of the back tooth and the second tip side of the front tooth of the joint body come into a state of tightly contacting the outer peripheral surface of the connection target pipe (P) under pressure to generate pipe extraction resistance (Z) composed of extraction resistance (Z B ) generated by the back tooth and extraction resistance (Z F ) generated by the front tooth , wherein the cap nut includes at least a tapered section with a reduced-diameter tip provided at an intermediate area of an hole part of the cap nut , wherein while the substantially cylindrical thin part is in a free state, the first tip side of the back tooth and the second tip side of the front tooth are arranged parallel to each other in such a manner that the first tip side is placed radially inwardly from the second tip side , and a slope angle at a tip of the tapered section with reduced-diameter tip, and the shape and dimension of the tip head are set in such a manner that, in the tightly pressure-contacting state, the second tip side projects further in a radially inward direction than the first tip side or the second tip side and the first tip side are at the same position as viewed in a radial direction. the extraction preventing tooth part is formed at a tip having a tip head of a substantially cylindrical thin part of a projecting shape provided at a tip of the joint body , the extraction preventing tooth part includes a back tooth and a front tooth arranged at a tiny interval (W 36 ), the back tooth has a trapezoidal or substantially trapezoidal sectional shape with a linear first tip side as an upper side, the front tooth has a trapezoidal or substantially trapezoidal sectional shape with a linear second tip side as an upper side, and as the cap nut threadedly moves forward, the first tip side of the back tooth and the second tip side of the front tooth of the joint body come into a state of tightly contacting the outer peripheral surface of the connection target pipe (P) under pressure to generate pipe extraction resistance (Z) composed of extraction resistance (Z B ) generated by the back tooth and extraction resistance (Z F ) generated by the front tooth , wherein the cap nut includes at least a tapered section with a reduced-diameter tip provided at an intermediate area of an hole part of the cap nut , wherein while the substantially cylindrical thin part is in a free state, the first tip side of the back tooth and the second tip side of the front tooth are arranged parallel to each other in such a manner that the first tip side is placed radially inwardly from the second tip side , and a slope angle at a tip of the tapered section with reduced-diameter tip, and the shape and dimension of the tip head are set in such a manner that, in the tightly pressure-contacting state, the second tip side projects further in a radially inward direction than the first tip side or the second tip side and the first tip side are at the same position as viewed in a radial direction. <EOS>