PROBLEM TO BE SOLVED: To provide a sealant film which exhibits high laminate strength to a base material layer, is excellent in slidability, and exhibits a high biomass degree of at least 45% as a whole to reduce an environmental load thereof, and to provide a packaging material using the sealant film, and a packaging bag.SOLUTION: There is provided a sealant film being a sealant film is layered on the base material layer and is a multilayer film comprising one or more layers 1 each comprising a petroleum-derived polyethylene resin and one or more layers 2 each comprising a plant-derived polyethylene resin. The outermost surface layer for forming a surface A on which the base material layer is layered is the layer 1 comprising the petroleum-derived polyethylene resin. In the petroleum-derived polyethylene resin, an area ratio of a low molecular weight area having the molecular weight equal to or lower than 1,000 is equal to or lower than 0.5 area% of the total peak area in a molecular weight distribution char
