To completely remove powder and dust stuck on the peripheral surface of an air cleaner without fixing the air cleaner and regulating the distance between the cleaner and an air nozzle.

The distance of the air nozzle 4 is kept almost constant regardless of the size of the air cleaner W by only mounting the air cleaner W on the rollers 1 and 1 by disposing the air nozzle 4 between a pair of rollers 1 and 1 disposed in parallel and also the powder and dust stuck on the surface of the cleaner are completely removed by supplying pressurized air to each chamber sectioned at the air nozzle 4 in order from one side to the other side by blowing the air in the longitudinal direction in order without moving the air nozzle 4 in the shaft direction.