A pipe joint , comprising: a first portion having an outer peripheral surface to be brought into contact with an inner peripheral surface of a pipe which is a first connection target; a second portion adjacent to the first portion in an axial direction of the first portion a third portion connected to a pipe which is a second connection target; a fourth portion between the second portion and the third portion ; and a protruding portion configured to protrude outward from a part of the second portion in a radial direction of the second portion , wherein: the axial direction of the first portion and an axial direction of the second portion are parallel to each other; the protruding portion has a leading end facing outward in the radial direction of the second portion ; the leading end is located on an outside of the outer peripheral surface of the first portion in a radial direction of the first portion and the radial direction of the second portion ; and an axial direction of the third portion and an axial direction of the fourth portion are perpendicular to the axial direction of the first portion ; characterized in that an outer diameter of the second portion is smaller than an outer diameter of the first portion ; the protruding portion is within a range from one end to the other end of the third portion in the axial direction of the first portion . a first portion having an outer peripheral surface to be brought into contact with an inner peripheral surface of a pipe which is a first connection target; a second portion adjacent to the first portion in an axial direction of the first portion a third portion connected to a pipe which is a second connection target; a fourth portion between the second portion and the third portion ; and a protruding portion configured to protrude outward from a part of the second portion in a radial direction of the second portion , wherein: the axial direction of the first portion and an axial direction of the second portion are parallel to each other; the protruding portion has a leading end facing outward in the radial direction of the second portion ; the leading end is located on an outside of the outer peripheral surface of the first portion in a radial direction of the first portion and the radial direction of the second portion ; and an axial direction of the third portion and an axial direction of the fourth portion are perpendicular to the axial direction of the first portion ; the axial direction of the first portion and an axial direction of the second portion are parallel to each other; the protruding portion has a leading end facing outward in the radial direction of the second portion ; the leading end is located on an outside of the outer peripheral surface of the first portion in a radial direction of the first portion and the radial direction of the second portion ; and an axial direction of the third portion and an axial direction of the fourth portion are perpendicular to the axial direction of the first portion ; characterized in that an outer diameter of the second portion is smaller than an outer diameter of the first portion ; the protruding portion is within a range from one end to the other end of the third portion in the axial direction of the first portion . <EOS>