A resin-made pipe joint comprising: a joint body having: a body cylinder portion in which a flow path for a fluid is formed; an outer cylinder portion which is coaxially projected from the body cylinder portion in one axial direction; and an inner cylinder portion which is placed radially inside the outer cylinder portion, and which is coaxially projected from the body cylinder portion in a same direction as the outer cylinder portion so that a projection end is located on a side of the body cylinder portion with respect to a projection end of the outer cylinder portion, a groove portion which opens in one axial direction being formed while being surrounded by the body cylinder portion, the outer cylinder portion, and the inner cylinder portion; a sleeve having: a cylindrical fitting portion which is detachably fitted to a radially inner side of the outer cylinder portion; a cylindrical coupling portion which is projected from the fitting portion in one axial direction, and which is press-insertable into a one longitudinal end portion of a tube; and a cylindrical inserting portion which is coaxially projected from the fitting portion in another axial direction, and which is inserted into the groove portion from an opening portion of the groove portion, the sleeve being connectable to or detachable from the joint body in a state where the sleeve is coupled to the tube; and a fastening member which enables the tube to be fastened to the joint body through the sleeve, wherein the joint body and the sleeve are produced by using a fluorine resin, the inserting portion has a radial width which is larger than a radial width of the groove portion, and is configured to, when the fitting portion is to be fitted to the radially inner side of the outer cylinder portion, be press-inserted into the groove portion, a sealing portion which seals between an inner circumferential surface of the inserting portion and an outer circumferential surface of the inner cylinder portion is formed by press-inserting the inserting portion into the groove portion, and, characterised in that when, with respect to the inserting portion and the groove portion, an insertion rate L1/L2 of the press insertion length L1 of the inserting portion at completion of the press insertion into the groove portion, to the depth L2 of the groove portion is indicated by X, and a multiplying factor D1/D2 of the radial width D1 of the inserting portion to the radial width D2 of the groove portion is indicated by Y, the resin-made pipe joint has the insertion rate X and multiplying factor Y which are within a range that is defined by following Expressions 1) and 2): Y = − 0.218 ⁢ X + 1.218, Y = − 0.67 ⁢ X + 1.67. a joint body having: a body cylinder portion in which a flow path for a fluid is formed; an outer cylinder portion which is coaxially projected from the body cylinder portion in one axial direction; and an inner cylinder portion which is placed radially inside the outer cylinder portion, and which is coaxially projected from the body cylinder portion in a same direction as the outer cylinder portion so that a projection end is located on a side of the body cylinder portion with respect to a projection end of the outer cylinder portion, a groove portion which opens in one axial direction being formed while being surrounded by the body cylinder portion, the outer cylinder portion, and the inner cylinder portion; a sleeve having: a cylindrical fitting portion which is detachably fitted to a radially inner side of the outer cylinder portion; a cylindrical coupling portion which is projected from the fitting portion in one axial direction, and which is press-insertable into a one longitudinal end portion of a tube; and a cylindrical inserting portion which is coaxially projected from the fitting portion in another axial direction, and which is inserted into the groove portion from an opening portion of the groove portion, the sleeve being connectable to or detachable from the joint body in a state where the sleeve is coupled to the tube; and a fastening member which enables the tube to be fastened to the joint body through the sleeve, wherein the joint body and the sleeve are produced by using a fluorine resin, the inserting portion has a radial width which is larger than a radial width of the groove portion, and is configured to, when the fitting portion is to be fitted to the radially inner side of the outer cylinder portion, be press-inserted into the groove portion, a sealing portion which seals between an inner circumferential surface of the inserting portion and an outer circumferential surface of the inner cylinder portion is formed by press-inserting the inserting portion into the groove portion, and, characterised in that when, with respect to the inserting portion and the groove portion, an insertion rate L1/L2 of the press insertion length L1 of the inserting portion at completion of the press insertion into the groove portion, to the depth L2 of the groove portion is indicated by X, and a multiplying factor D1/D2 of the radial width D1 of the inserting portion to the radial width D2 of the groove portion is indicated by Y, the resin-made pipe joint has the insertion rate X and multiplying factor Y which are within a range that is defined by following Expressions 1) and 2): Y = − 0.218 ⁢ X + 1.218, Y = − 0.67 ⁢ X + 1.67.