A method and apparatus of inspecting a defect of a surface of a sample in which a laser beam is irradiated on a sample surface so that at least a part of an illumination field of the laser beam illuminates a first area of the sample surface, a plurality of scattered light rays from the first area caused by the irradiation is detected with a plurality of detectors, detection errors of inclination of an illumination apparatus and a sensor for the plurality of scattered light rays detected by the plurality of detectors are corrected, at least one of adding and averaging the corrected plurality of scattered light rays, and a defect on the sample surface is determined based on the plurality of scattered light rays in accordance with the correction of errors of inclination of the illumination apparatus and the sensor.