Workpieces, which are conveyed by a conveying device along a conveying path, are heated by a heating and degreasing coil. Then, resin powder is downwardly sprayed from a nozzle of a coating device to each corresponding one of the workpieces, which are conveyed by the conveying device. The workpieces are thereafter heated by a heating and curing coil. At each of the heating coils, a dummy member, which is made of an electrically conductive material, is displaced from a retracted position to a forward position, which is located between the corresponding heating coil and a corresponding adjacent part of the conveying path of the conveying device, when an empty one of mount locations of the conveying device reaches the forward position of the dummy member.