Abstract: Provided are a foreign substance removal method and foreign substance removal device that have excellent continuous operation stability for sheets and excellent foreign substance removal performance, during removal of foreign substance. Suction boxes (3a, 3b) are arranged at a position between two conveyance support bodies (1a, 1b) having an arrangement interval fulfilling prescribed conditions, said position having vertical symmetry relative to the sheet (2). Air is jetted towards the sheet (2) from air nozzles (4a, 4b) arranged inside the suction boxes (3a, 3b). Foreign substances are detached from upon the sheet (2) and the detached foreign substances are recovered using suction air having an average suction airspeed of 0.8-1.2 m/sec from openings (5a, 5b) in the suction boxes (3a, 3b).