A defect inspection apparatus for inspecting a surface of a sample includes a stage for holding the sample, an illumination optical system that irradiates a laser beam to form a linear illuminated area on the surface of the sample, a detection optical system, and a signal processing system. The detection optical system includes a detector device having a plurality of pixels for detecting light scattered from the linear illuminated area of the surface of the sample, and that outputs in parallel a plurality of detection signals having mutually different sensitivities acquired from the plurality of pixels of the detector device. The signal processing system selects an unsaturated detection signal from the plurality of detection signals and detects a defect in accordance with the selected detection signal.