PURPOSE: To efficiently suppress the clogging of a meshed filter by attracting and repulsing a magnetic member by a change of magnetic fields to cause displacement and to consequently impart vibration to the meshed filter and regulating the displacement of the magnetic member until the max. attraction force is generated by the change of the magnetic fields.

CONSTITUTION: The meshed filter 20 consisting of a nonmagnetic material is disposed at a frame body 19 of a separating device 18 and one side thereof is clamped by a flexible sheet 21 and is supported by a supporting member 22. The meshed filter 20 separates coexisting foreign matter while moving only the magnetic materials between both upper and lower magnet rollers 25 and 26. A diaphragm 23 which imparts vibration to the meshed filter 20 is installed to the supporting section 19a of the frame body 19 in this constitutiuon. A magnet member 23a facing the upper magnet roller 26 is disposed at the front end of the diaphragm 23. Further, the displacement of the diaphragm 23 is regulated until the max. attraction force is generated in the magnet member 23a. As a result, the clogging of the meshed filter 20 is efficiently suppressed.