To make it possible to obtain sufficient magnetic force in spite of a small size and lighweightness and to prevent the damage to a belt by arranging a first permanent magnet the N pole of which is directed toward the belt surface and a second permanent magnet the S pole of which is directed toward thereto apart from each other in a direction orthogonal with the progressing direction of the belt.

A driving pulley 5 and a driven pulley 6 are respectively pivotally supported at a pair of bearings 3 and a pair of bearings 4 fixed to a frame 2. The driving pulley 5 is driven by a hydraulic motor 8 via a stationary shaft coupling 9 to turn counterclockwise the belt 7 put on the driving pulley 5 and the driven pulley 6. The first permanent magnet 20 the N pole of which is directed toward the belt 7 surface and the second permanent magnet 21 the S pole of which is directed toward thereto are fixed via a yoke 22 in a frame 2 within the internal space enclosed by the belt 7. The outside surface of the belt 7 arranged with these permanent magnets 20, 21 is positioned in proximity to the upper part of raw materials 31 to be sorted and the magnetic foreign matter where the raw materials 31 to be sorted coexist is attracted to the outside surface of the belt 7 and is transported.