PROBLEM TO BE SOLVED: To provide a sealant film that exhibits high laminate strength with a base material layer, is excellent in slipperiness and reduces an environmental burden because it exhibits a high biomass degree of at least of 45% as a whole and to provide a packaging material and a packaging bag each using the sealant film.SOLUTION: A sealant film is used by laminating on a base material layer 4 and is a multilayer laminate film composed of one or more layers comprising a layer 1 comprising a petroleum-derived polyethylene resin and one or more layers comprising a layer 2 comprising a plant-derived polyethylene resin. The outermost surface layer forming the lamination surface of the base material layer is the layer 1 comprising a petroleum-derived polyethylene resin and the petroleum-derived polyethylene resin has an area ratio of a low molecular weight region having a molecular weight of 1,000 or less of 0.5 area% or less based on the total peak area in a molecular weight distribution chart obtained
