To provide a method for removing particles on the surface of a basic material in which the workability of stripping work is enhanced while reducing the residue on the surface of the basic material.

(a) 20-78.9 pts.wt. of radical polymeric monomer, (b) 0.1-10 pts.wt. of a vinyl monomer having a reactive silyl group and copolymerable with the (a) radical polymeric monomer, (c) 1-20 pts.wt. of radical polymeric silicone based macromonomer copolymerable with the (a) radical polymeric monomer, and (d) 20-50 pts.wt. of (meta)acrylonitrile are copolymerized to provide a copolymeric film on the surface of a basic material and then the film is stripped off therefrom. Since the copolymer thus provided exhibits high adhesion to the surface of the basic material and good balance with the toughness of the film, the film can be stripped smoothly and contamination on the surface of the basic material can be suppressed after stripping the film.