There is provided a multilayer laminate film with easy unsealability, heat resistance and easy cuttability, having a seal layer (A) and a base material layer (B), the multilayer laminate film containing the seal layer (A) and the base material layer (B) composed of a mixture of 10-50 parts by weight of high-density polyethylene and 50-90 parts by weight of polypropylene, laminated on the seal layer (A) in one layer or two or more layers, wherein the base material layer (B) is composed of one member selected from the group consisting of (a) an ethylene/butene copolymer with a density of 0.93 g/cm3-0.94 g/cm3, polymerized using a multisite catalyst, (b) high-density polyethylene with a density of 0.945 g/cm3-0.965 g/cm3 and (c) an ethylene/propylene block or random copolymer, further wherein the layer thickness of the seal layer (A) is 1 μm-20 μm while the layer thickness of the base material layer (B) is 20 μm-100 μm, as well as a packaging container and packaging bag employing it as a lid material.