An apparatus for inspecting a substrate surface is provided, which includes illumination optics for irradiating the substrate surface linearly with rectilinearly polarized light from an oblique direction, detection optics for acquiring images of the substrate surface, each of the images being formed by the light scattered from the light-irradiated substrate surface, and means for comparing an image selected as an inspection image from the plurality of substrate surface images that the detection optics has acquired to detect defects, and another image selected from the plural images of the substrate surface as a reference image different from the inspection image; the illumination optics being formed with polarization control means for controlling a polarizing direction of the light according to a particular scanning direction of the substrate or a direction orthogonal to the scanning direction.