A polyolefin resin composition for metallized films, having superior high-impact properties and heat-sealability and also superior printability and adhesive properties of metallized surface and further a good taken-up figure of rolled film is provided, which composition is obtained by blending a crystalline propylene-.alpha.-olefin copolymer containing 70% by weight or more of propylene component and having a crystalline m.p. of 150.degree. C. or lower, with a high density polyethylene having a density of 0.940 g/cm.sup.3 or higher, in blending ratios of 96 to 80% by weight of the copolymer and 4 to 20% by weight of the polyethylene, the ratio of the melt flow rate of the polyethylene to that of the copolymer being .gtoreq.0.7.