Abstract: In accordance with the present invention, there are provided ethylene copolymers composed of structural units (a) derived from ethylene and structural units (b) derived from .alpha.-olefin of 3-20 carbon atoms, said ethylene copolymers having?A! a density of 0.85-0.92 g/cm.sup.3,?B! an intrinsic viscosity ?.eta.! as measured in decalin at 135.degree. C. of 0.1-10 dl/g,?C! a ratio (Mw/Mn) of a weight average molecular weight (Mw) to a number average molecular weight (Mn) as measured by GPC of 1.2-4, and?D! a ratio (MFR.sub.10 /MFR.sub.2) of MFR.sub.10 under a load of 10 kg to MFR.sub.2 under a load of 2.16 kg at 190.degree. C. of 8-50, and being narrow in molecular weight distribution and excellent in flowability.