PURPOSE: To mount a filter member regardless of the kind of a ventilator and to inexpensively replace the same by covering an exhaust port with a sheet-like filter member wider than the exhaust port and pressing the periphery of the filter member by magnet holders to fix the same.

CONSTITUTION: An exhaust port 19 is covered with a sheet-like filter member 18 wider than the exhaust port 19 and the periphery of the filter member 18 is pressed by magnet holders 13 to be fixed. As a result, regardless of the kind of a ventilator or a range hood, the filter member can easily be mounted and inexpensively be replaced.