Catching grooves (34) extending in the axial direction are formed in the cylindrical outer surface of a brush base (35) that has a slender, substantially cylindrical shape and made of a twistable material. Brush attaching portions (43) of brush members (41) and blade attaching portions (47) of scraping members (42) are respectively secured in the catching grooves (34) so that axially aligned bristles (44) of each brush member (41) and an axially extending blade (46) of each scraping member (42) project from the cylindrical outer surface of the brush base (35). Receiving members (53) are respectively fitted to both ends of a shaft (51) inserted through a shaft insertion hole (39) of the brush base (35). By rotating the receiving members (53) in opposite directions, the brush base (35) is twisted in a spiral and secured. By eliminating the necessity of forming the brush base (35) in a twisted shape beforehand by means of twist extrusion molding, the invention facilitates production of the brush base (35). Adjusting the degree of twisting the brush base (35) ensures a sufficient twisting precision.