and n are 0 or positive integral numbers, (b) immersing the substrate in a mixed monomer solution, for example, mainly containing acrylamide and N,N'-methylenebisacrylamide, (c) adding diammonium cerium (IV) nitrate, and (d) carrying out graft polymerization of the above mentioned mixed monomers on the substrate surface under normal pressure, wherein an amount of diammonium cerium (IV) nitrate ad