A tube joint for a fuel tank includes a joint body having a tubular shape, and a barrier layer covering the inner surface of the joint body. The joint body is formed of a material which is weldable to a tank body, and the barrier layer is formed of a material which has fuel impermeability and a predetermined hardness. The barrier layer has an extension portion extending from a distal end of the joint body along an axial direction of the joint body. The extension portion includes a projecting portion which protrudes radially and outwardly of the extension portion at or adjacent to a proximal end of the extension portion such that a seal groove is formed between the projecting portion and the joint body, and a nail portion which protrudes radially and outwardly of the extension portion at or adjacent to a distal end of the extension portion.