An ethylene-.alpha.-olefin copolymer containing monomer units derived from ethylene and monomer units derived from an .alpha.-olefin having 4 to 20 carbon atoms, and having a density of 890 to 970 kg/m.sup.3, an activation energy of flow of 50 kJ/mol or more, a molecular weight distribution of 3 or more determined by a gel permeation chromatography, and the number of inflection points of 3 or less on a melting curve obtained by a differential scanning calorimetry within a temperatures ranges of from 25.degree.C. to an end point of melting.