A method and apparatus for inspecting pattern defects emitting a laser beam, adjusting a light-amount of the laser beam, converting the light-amount adjusted laser beam into a slit-like laser light flux, lowering coherency of the slit-like laser light flux, and irradiating a sample with the coherence reduced slit-like laser light flux. An image of reflection light from the sample is obtained, and a detector is provided which includes the image sensor for receiving the image of the reflection light and for converting it into a detected image signal. An image processor is provided for detecting defects on patterns formed on the sample in accordance with the detected image signal.