PURPOSE: To properly position a floor plate in a short time and provide a stable clamping state by forming a bulge on both ends of the floor plate where in contact with a floor.

CONSTITUTION: A floor plate 3 is formed to have a bulge made of elastic materials 31 and 31 such as a felt, a sponge, a rubber and plastic attached to the sides in contact with a floor 2 at both ends. As a result, the plate 3 is fixed on the floor 2 via the bulge at both ends, and does not turn even when a vacuum cleaner or a person's foot touches. Also, the plate 3 is positioned at one side for the leg 11 of furniture 1, and when made to slide right and left, turns about a contact section between the floor 2 and the elastic member 31. Thereby the other side of plate 3 can be easily be positioned.