a polyolefin film which comprises a polypropylene base layer and at least one top layer comprising a propylene polymer , wherein the base layer is formed of an isotactic polypropylene and the top layer of a copolymer of an o - olefin having 2 to 8 carbon atoms and a syndiotactic propylene , has high sealed - seam strength and excellent optical properties and is useful as , for example , a packaging material .