Abstract: An cylindrical convex portion of which opposite ends are open is integrally formed onto a fuel tank made of RDPE therewith so as to inwardly extend in the fuel tank, to provide an opening thereon. A press-fit portion of a filler hose connecting pipe made of PA as a tubular member is press-fitted in the cylindrical convex portion to connecting the tubular member to the fuel tank. At least one annular projection is provided on the outer peripheral surface of the press-fit portion of the tubular member so as to bite in the inner peripheral surface of the cylindrical connvex portion. A face of the annular projection in direction axially of one end of tubular member is formed so as to extend outwardly and inclinedly with respect to the axial direction of the tubular member form one end toward the other end thereof.