An Inspection apparatus and method includes utilizing an emitter which emits a light beam, an illumination optical system, a detection optical system, and a processor. The illumination optical system includes a polarization controller, a coherence reducer, and an objective lens, for illuminating a specimen with a polarization condition controlled and coherency reduced light beam through the objective lens. The detection optical system includes an imaging lens and a sensor for detecting an image of the specimen illuminated by the light beam through the illumination optical system. The processor processes a signal outputted from the sensor and detects a defect on the specimen.