A vulcanized, ethylene/α-olefin copolymer rubber composition obtained by vulcanizing an unvulcanized rubber composition comprising 100 parts by weight of a rubber composition consisting of 0-99% by weight of an ethylene/α-olefin copolymer rubber and 100-1% by weight of an ethylene/α-olefin copolymer rubber containing an α,β-unsaturated carboxylic acid and/or a derivative thereof; and 5-100 parts by weight of a polyamide resin, wherein an ethylene/α-olefin copolymer rubber is at least one selected from ethylene/α-olefin copolymers and ethylene/α-olefin/non-conjugated diene copolymers. The vulcanized, ethylene/α-olefin copolymer rubber composition of the present invention has a high hardness and is excellent in weather resistance and thermal resistance as compared with natural rubbers and general-purpose rubbers.