According to the present invention, for a pattern inspection apparatus that compares images in corresponding areas of two patterns that are identical and that determines an unmatched portion between the images is a defect, a plurality of detection systems and a plurality of corresponding image comparison methods are provided. With this configuration, the affect of uneven brightnesses for a pattern that occurs due to differences in film thicknesses can be reduced, a highly sensitive pattern inspection can be performed, a variety of defects can be revealed, and the pattern inspection apparatus can be applied for processing performed within a wide range. Furthermore, the pattern inspection apparatus also includes a unit for converting the tone of image signals of comparison images for a plurality of different processing units, and when a difference in brightness occurs in the same pattern of the images, a defect can be correctly detected.