PURPOSE: To prevent the adhesion of a polyvinylidene chloride layer to a hot plate or a mold from occuring by providing the polyvinylidene chloride layer to the surface of a plastic sheet through an adhesive and applying a release agent dissolved in a solvent of polyvinylidene chloride to the outside thereof.

CONSTITUTION: As a constituent material of a plastic sheet, hard polyvinyl chloride, polystyrene, non-stretched polypropylene, non-stretched high density polyethylene, polyethylene terephthalate or polycarbonate are designated. In order to form a polyvinylidene chloride layer to the plastic sheet, a method for applying a polyvinylidene chloride emulsion to dry the formed layer is used. As the kind of a release agent, a silicone type, an ester wax type, a paraffin wax type, a metal soap type such as calcium stearate or zinc stearate, a stearic acid type or a bisamide type are used.