PURPOSE: To improve the environment for driving, by connecting a right and a left fenders to each other with a central rear cover part and providing the rear cover part with an expanded portion.

CONSTITUTION: A right and a left fenders 1, 2 are connected to each other by a central rear cover part 3 to constitute a floor cover. The rear cover part 3 is provided with an expanded portion 7a of such shape that attachments such as tools can be housed. The portion 7a is expanded backward, namely, away from the driver's seat located in front of the rear cover part 3. The expanded portion 7a functions as a reinforcing rib to increase the rigidity of the rear cover part 3 enough to prevent the occurrence of humming noise in driving so that it is quiet around the driver's seat. The environment for driving is thus improved.