PURPOSE: To effectively prevent electrostatic troubles, by spreading a carpet underlay on the setting bed under a floor and covering it with an electric conductive sheet and further laying a carpet thereon.

CONSTITUTION: A carpet underlay 3 is installed on the setting bed G under a floor and covered with an electroconductive sheet 1 thereon and further, a carpet 2 is spread thereon. Or after the setting bed G under the floor has been covered with the electric conductive sheet 1 without a carpet underlay, the carpet 2 is laid down. A wooven cloth, a non-wooven cloth, or other electric conductive sheets bearing aluminum foil sheet, carbon fiber or metallic coating synthetic fiber, etc., as much as 2-40% are favorable as the conductive sheet 1. As a result, even if the mixing cent of antistatic materials is not increased in the carpet, or the use condition is severe like in a low temperature, the antistatic characteristic is greatly improved.