PURPOSE: To easily and completely remove magnetic materials mixed into powder by disposing a suction means in a guide pipe having a collar, moving the suction means together with the guide pipe and moving the suction means so as to cross the collar of the guide pipe.

CONSTITUTION: The guide pipe 25 which has the collar 26 on the outside surface and is internally and freely movably equipped with magnets 41 is disposed across powder falling passages 1, 2. The magnets 41 are moved to the guide pipe 25 of the part crossing the powder passages 1, 2 to drop the powder and to attract the magnetic materials mixed into the powder on the surface of the guide pipe 25. The guide pipe 25 is thereafter moved to outside the powder passages 1, 2 and the magnets 41 are moved in the direction crossing the collar 26 of the guide pipe 25. The magnetic materials attracted to the surface of e guide pipe 25 are then peeled and dropped.