PURPOSE: To form a fender body to a cylindrical form when air is poured into the fender, while form the fender body to a flat plate shape when air is discharged, by laminating an outer surface rubber layer, inner surface rubber layer and a reinforcing layer similarly in bent form, and installing an air pouring valve at the mirror part of the fender body.

CONSTITUTION: An inner surface rubber layer 3 as the innermost layer is placed at the center of a reinforcing layer 4 in developed state, and attached in bent form and laminated by the similar order and operation to the inner surface rubber layer 3. Further, the integral form of the inner surface rubber layer 3 and the reinforcing layer 4 is placed at the center of an outer surface rubber layer 5 in developed state, and also the outer surface rubber layer 5 is bent and laminated similarly as in case of the inner surface rubber layer 3 and the reinforcing layer 4. At one edge part of a fender body W thus constituted, an air pouring valve 7 is installed. Accordingly, when air is poured into the fender beam body W, it can be formed to a cylindrical form, while if air is discharged, the fender can be formed to a flat plate shape.