1. A defect inspecting apparatus which inspects a defect in a sample, a pattern being formed in a sample surface, the defect inspecting apparatus comprising: a stage on which the sample is placed; a light source; an illumination optical system for epi-illumination of the sample surface with light emitted from the light source and transmitted through a polarizer and an objective lens; a detection optical system which detects a pupil image of the objective lens formed with the light of illumination reflected from the sample surface and transmitted through the objective lens and an analyzer, the analyzer satisfying a cross-nichols condition along with the polarizer; and a detecting unit which compares the obtained pupil image to a previously-stored pupil image to detect the defect in the sample.