PROBLEM TO BE SOLVED: To provide a film damage detection method and a film damage detection device capable of highly accurately detecting damage of a film regardless of proficiency of an operator.SOLUTION: A film damage detection device that is one embodiment of this invention photographs an image of a surface of a steel plate S containing a region irradiated with electron beam in irradiation of the electron beam, calculates luminance at each position in the region irradiated with the electron beam from the photographed image, determines that damage of a film occurs at a position where the calculated luminance exceeds a predetermined threshold, and thereby can highly accurately detect damage of the film regardless of proficiency of an operator.SELECTED DRAWING: Figure 5
