Abstract: A polishing method able to easily flatten unevenness formed on the surface of a film to be polished and able to efficiently polish the film flat while suppressing damage to an interlayer insulating film below the film, comprising, when polishing an object having a film such as an interconnection layer formed burying interconnection grooves formed in an insulating film of a substrate, supplying a polishing solution over the surface to be polished at least substantially parallel to the surface to preferentially remove by polishing the projecting portions of the film and flatten the surface by the shear stress of the processing solution or arranging a cathode member facing the surface and supplying an electrolytic solution containing a chelating agent between the surface and cathode member while supplying voltage between the film and the cathode member to preferentially remove by polishing the projecting portions of the film and flatten the surface by the shear stress of the electrolytic solution, and a polishin