Inspection method and inspection device for membrane electrode assembly

An inspection method of a membrane electrode assembly includes a first process of acquiring an X-ray transmission image of the membrane electrode assembly, a second process of identifying a luminance-reduced region having a luminance lower than a luminance of a surrounding region in the X-ray transmission image acquired in the first process, a third process of correcting the luminance of the luminance-reduced region identified in the second process, in accordance with a planar size of the luminance-reduced region, based on a correlation between a planar size of a foreign matter in the membrane electrode assembly and change in luminance due to diffraction of X-rays, and a fourth process of finding a thickness of the foreign matter in the membrane electrode assembly based on the luminance corrected in the third process.