A package bag in a rectangular-like shape for enclosing an object to be packed W, which package bag is configured by a film F having a sealant layer 20 to be fusion-bonded so as to cause interfacial peeling, ply separation, or cohesive failure, and thermally sealed portions provided in at least three sides or four sides 3 in a state enclosing the object to be packed in an inside of the package bag, wherein at least one of the thermally sealed portions 4 along one of the sides is a strippable seal 8a, which is associated with an unsealed portion 8 as stripping margins positioned between the strippable seal 8a and an film edge 6; and the strippable seal 8a is formed in at least a part of the one of the thermally sealed portions 4 to be in a wave-like shape or in a V-like shape protruding toward the film edge 6.