A surface treating apparatus treats a substrate surface by rotating a cylindrical polishing member in a state where the polishing member makes contact with the substrate surface. A polishing liquid is supplied to a polishing liquid passage that is provided in a central portion of the polishing member, and the polishing liquid is supplied to the substrate surface by rotating the polishing member while filtering the polishing liquid by a foam member provided on an outer periphery of the polishing liquid passage. Aperture diameters of the foam member are larger on the side of the polishing liquid passage than on the outside of the polishing member.