An ethylene type polymer composition comprising 20 to 90% by weight of an ethylene type polymer (A) and 80 to 10% by weight of an ethylene type polymer (B). The ethylene type polymer (A) is an ethylene polymer or a copolymer of ethylene and an .alpha.-olefin of 3 to 20 carbon atoms and has a density (d.sub.A) of 0.96 to 0.980 g/cm.sup.3 and an intrinsic viscosity (.eta.) of 0.5 to 3.0 dl/g. The ethylene type polymer (B) is an ethylene polymer or a copolymer of ethylene and an .alpha.-olefin of 3 to 20 carbon atoms and has a density (d.sub.B) of 0.91 to 0.965 g/cm.sup.3 and an intrinsic viscosity (.eta.) of 1.0 to 10 dl/g. At least one of the ethylene type polymers (A) and (B) is an ethylene type polymer prepared by the use of a metallocene catalyst. The ethylene type polymer composition has the properties: d.sub.A /d.sub.B is larger than 1; the density is 0.940 to 0.970 g/cm.sup.3 ; the MFR is of 0.005 to 20 g/10 min; the MFR and the melt tension (MT) satisfy the relation log(MT).gtoreq.-0.4 log(MFR)+0.7; and the diametrical swell ratio exceeds 1.35. From this composition, molded articles having excellent mechanical strength and rigidity can be obtained.