Cover for Fuel Tank

A fuel tank cover () is provided with a flange unit () closing an opening of a fuel tank, and a joint member () configured to be connected to the flange unit () movably in the upward/downward direction. The flange unit () includes a side tubular portion () extending in the upward/downward direction. The joint member () includes a columnar portion () extending in the upward/downward direction. The columnar portion () is inserted into the side tubular portion () movably in the upward/downward direction. A metal retainer () is provided to cover an outer circumferential surface of the columnar portion ().