Abstract: A cover for forming a space for coating is provided above an electroconductive belt conveyor for adjusting an electric field at an end portion of a flat plate-like object to be coated, electrostatic powder coating guns pointed at the object to be coated on the belt conveyor in the space for coating are provided, and means for introducing air into the space for coating and means for exhausting the air are respectively provided. As a result, the strength of the electric field formed from the electrostatic powder coating guns to the electroconductive belt conveyor and the object to be coated is made uniform through their entire surface so that the thickness of a powder layer to be adhered to the object to be coated is made uniform from its central portion to an end portion. Consequently, the waste of the powder coating material is prevented, and local cracks in a portion having a great thickness generated when the coated object is bent are prevented.

Abstract: A powder coating booth a function of supplying air though its ceiling. Sidewalls of the booth is formed from an insulating material or a semiconductor. A belt conveyor is disposed at the bottom of the booth. An electric field is formed so that it extends from a paint gun to the conveyor belt. The majority of oversprayed powder paint produced during painting becomes attached to the upper surface of a portion of the conveyor belt, is carried, together with this belt portion, to the outside of the booth, and is recovered from the conveyor by a blowing-type of static eliminator, thereby minimizing the mount of oversprayed powder paint mixed in an exhaust of the booth drawn through the sidewall.