A sheet processing apparatus takes out postal matters that are inserted by a take-out roller, and separates them in sheets by a feed roller (21) and a reversing roller (22), and feeds into the apparatus. A cleaning roller (27) having rubber sponges having foamed vesicles in mean diameter 50 to 500 µm is provided to the feed roller (21) in contact with it. Paper-dusts on the surfaces of the feed roller (21) and the reversing roller (22) are removed by driving this cleaning roller (27) to rotate at a velocity equal to or higher than a rotating speed of the feed roller (21).