A new casting process of organic glass material for optical uses was developed by radiation-induced polymerization of supercooled monomeric systems including methyl methacrylate prepolymer at low temperatures. The formation of two types strain, that is, the thermal stream type strain and the inner stress strain was studied in casting. Those strains were suppressed remarkably and the polymer with no strain and stress was obtained efficiently in the radiation casting at low temperatures. © 1979.