An elastomer composition for light-resistant covering materials, and covering materials for industrial parts which comprise the composition, are obtainable by partially cross-linking a mixture comprising (A) 100 parts by weight in total of at least one terpolymer rubber having a 100°C Mooney viscosity (ML₁₊₄ 100°C) of 30 to 350 selected from ethylene-propylene-dicyclopentadiene terpolymer rubbers and ethylene-butene-1-dicyclopentadiene terpolymer rubbers, (B) 5 to 150 parts by weight of an olefinic polymer and (C) 0 to 150 parts by weight of a mineral oil or a mixture comprising 40 to 95% by weight of an oil-extended ethylene terpolymer rubber and 5 to 60% by weight of an olefinic polymer, the oil-extended ethylene terpolymer rubber comprising a terpolymer rubber component comprising at least one ethylene terpolymer rubber having a 100°C Mooney viscosity (ML₁₊₄ 100°C) of 30 to 350 ethylene propylene-dicyclopentadiene terpolymer rubbers and ethylene-butene-1-dicyclopentadiene terpolymer rubbers and 150 parts by weight or less of a mineral oil per 100 parts by weight of the terpolymer rubber component.