Conventionally, when a protective/insulation film is present above a film to be corrected, only a defect of the film to be corrected below such an upper-layer film is corrected without damaging the upper-layer film. A display region of a display device has an insulation film, a semiconductor film and a conductive film formed in a given pattern and stacked on a substrate. When at least one of a correction portion out of a correction portion which separates a short-circuit defect, a correction portion which connects an opening defect, a correction portion which removes a standard deviation defect, and a correction portion which separates a standard deviation defect of the pattern is corrected, at least one upper-layer film is present above a film to be corrected at the correction portion and the correction is applied to the film to be corrected while leaving the upper-layer film intact.