To provide an inspection method and an inspection device for inspecting a fold part and a flaw of a package formed of a soft packing film to have a bag shape.

This inspection method has: a plurality of illumination steps for irradiating polarized illumination light to an inspection object from each different direction; an imaging step for changing reflected light from the inspection object into a polarized state by a polarization means, imaging the light by an imaging means, and acquiring image data; and an image processing step for storing image data imaged by the imaging means, and performing various image processing to the image data. In the imaging step, image data imaged in each of the plurality of illumination steps are acquired successively, and in the image processing step, differential image data are generated by calculating a difference of a plurality of image data acquired in the imaging step, and a fold and a flaw of the inspection object are extracted by performing a prescribed calculation processing to the differential image data, to thereby determine whether the inspection object is a nondefective product or not.