Abstract: The chain polyene-group containing norbornene compound of the invention is represented by the formula [I]: ##STR1## wherein n is an integer of 1 to 5, R.sup.1 is an alkyl group of 1 to 5 carbon atoms, and R.sup.2 and R.sup.3 are each independently a hydrogen atom or an alkyl group of 1 to 5 carbon atoms.The unsaturated ethylene copolymer of the invention is a random copolymer of 30 to 92% by mol of (i) ethylene units, 6 to 70% by mol of (ii) specific .alpha.-olefin units and 0.1 to 30% by mol of (iii) units derived from the norbornene compound [I], where the molar ratio of (i)/(ii) is in the range of 40/60 to 92/8 and the unit (iii) is represented by the specific formula, and has an intrinsic viscosity [.eta.] of 0.05 to 10 dl/g.The novel unsaturated ethylene copolymer is excellent in weathering resistance, heat resistance and ozone resistance and has a high vulcanizing rate.