PURPOSE: To provide a crystalline pattern of high texture and excellent durability on the surface of a material by a method wherein a monomer dissolved in a solvent for swelling a high polymeric material is applied to the surface of the material, and monomeric crystals are radiation polymerized after evaporating off the solvent.

CONSTITUTION: A solution of a monomer capable of being crystallized and polymerized when subjected to irradiation is applied to the surface of a high polymeric material, particularly a plastic film. The solvent used in this case is selected so as to provide a property of swelling the high polymeric material. Next, the material is dried to evaporate the solvent, forming a crystalline layer of the monomer on the film surface. Then, radioactive rays are irradiated to polymerize the monomer. Subsequently, unpolymerized monomer is removed by using a solvent which dissolves the monomer but does not swell the base material, i.e., the high polymeric material.