A protective plate can be mounted to a fuel tank without using costly melt bonding and insert blow molding. A mounting recess is formed in the peripheral wall of a fuel tank (1) formed by blow molding, and a fixing element (3) for fixing a protective plate (2) to the fuel tank (1) can engage with the mounting recess. The mounting recess is open in two directions, that is, in the direction of mold removal in the blow molding and in the direction of the thickness of the protective plate which direction is generally perpendicular to the direction of the mold removal. The fixing element comprises a first clip (6) provided with elastic leg sections (62) fitted in the mounting recess in the direction of the mold removal, and also comprises a second clip (7) provided with elastic leg sections (72) penetrating through the protective plate and fitting in the first clip in the direction of the thickness of the protective plate. The protective plate is sandwiched between the first and second clips.