An object to be solved by the present invention is to provide a method for preparing a composition prepared by firmly coating the surface of a material with a biopolymer, and a composition prepared by this method wherein the surface of a material is firmly coated with a biopolymer. The present invention provides a method for coating with a biopolymer, which comprises coating the surface of a synthetic polymer with a biopolymer dissolved in a solvent comprising an organic fluorine compound.
