A layer (71), made from a material that is attracted by a magnet, is formed in at least part of a chamber component (70), which at least part makes in contact with a film forming material. A method for collecting a film forming material includes the steps of: (a) exfoliating an attachment (22) which has attached to a surface of the chamber component (70); and (b) collecting the attachment (22) by separating a fragment of the layer (71), which fragment has been exfoliated in the step (a), while causing the fragment to be attracted by a magnet (202a).