A defect inspection method includes an illumination light adjustment step of adjusting light emitted from a light source, an illumination intensity distribution control step of forming light flux obtained in the illumination light adjustment step into desired illumination intensity distribution, a sample scanning step of displacing a sample in a direction substantially perpendicular to a longitudinal direction of the illumination intensity distribution, a scattered light detection step of counting the number of photons of scattered light emitted from plural small areas in an area irradiated with illumination light to produce plural scattered light detection signals corresponding to the plural small areas, a defect judgment step of processing the plural scattered light detection signals to judge presence of a defect, a defect dimension judgment step of judging dimensions of the defect in each place in which the defect is judged to be present and a display step of displaying a position on sample surface and the dimensions of the defect in each place in which the defect is judged to be present.