PURPOSE: To prevent a floor carpet from being removed from a hooking member even if it is stepped over by shoes and the like by covering the upper part of a harness space with a carpet support member having almost the same height level as the lower surface of the floor carpet.

CONSTITUTION: A carpet support member 8 is formed into an L-shaped cross section consisting of a side section 8a that is almost equal in height to a total of the thicknesses of a fusible insulator 1 and a felt 2 stretching in the longitudinal direction of a car body along a side sill 5 and an upper wall section 8b. A downward claw 9 is formed on top of the upper wall section 8b and is hooked on a hook 10 that is formed into the flange 3a of a floor panel 3 so that the carpet support member 8 can not be moved. Since the side end 4a of the floor carpet 4 that is opposed to a harness space A is firmly supported by the carpet support member 8, the side end 4a of the floor carpet 4 is not removed from a kicking plate 6 even if is stepped over by shoes B.