PURPOSE: To prevent the surface stickiness of a molding and to increase its surface hardness, by applying an organic solvent solution of a specified surface hardener in curing a molding material comprising an unsaturated carboxylate ester monomer mixed with a catalyst.

CONSTITUTION: As a surface hardener is used at least one member selected from the group consisting of a peroxide, an amine and a sulfine, e.g., benzoyl peroxide, N,N-bis-(2-hydroxyethyl)-4-methylaniline, or benzenesulfinic acid. Namely, a solution of the above surface hardener in an organic solvent (e.g., ethanol) is applied to the surface of a molding in curing a molding material comprising an ethylenically unsaturated double bond-containing coaboxylate ester (e.g., tetramethylolmethane trimethacrylate), a polymerization catalyst (e.g., benzoyl peroxide), and an accelerator [N,N-bis(2-hydroxyethyl)-4-methylaniline] into the molding.