To obtain a resin for optical screen having necessary stiffness, reduced hygroscopic property and wave length dependency of the refractive index, used, for example, for Fresnel lens sheet, lenticular lenz sheet which are constituting members of a transmission type screen, or a material of a front panel each for a projection television set.

This methyl methacrylate based resin for optical screen is obtained by copolymerizing 65-85 wt.% of methyl methacrylate and 15-35 wt.% of an aromatic vinyl based monomer, based on the all monomers, and setting the sum of both monomers to ≥90 wt.%.