Both surfaces of fine ceramics used for electronic parts are covered with, for example, a resin, a ceramic alumina, or a solder. An automatic optical method for detecting cracks originating at the side faces of ceramic chips, the surfaces of which are covered with the mentioned materials, is developed and is reported. A laser beam is diffused into the specimen by illumination onto the side faces through an objective lens. When the specimen has a crack near the laser spot, the diffused laser light is reflected by the crack and the amount of radiant exitance near the crack is increased. The image of the side face is enlarged by the objective lens and detected by four photomultiplier tubes. It is clarified experimentally that it is possible to recognize the region surrounded by a close-ended crack wider than 20 μm and longer than 35 μm, or an open-ended crack longer than 50 μm, by detecting signals higher than the average level. Experimental results revel that the cracks in the ceramic parts can be detected automatically in a production line.