A defect inspection apparatus includes an illumination optical unit for obliquely illuminating an object with a slit-like shaped laser, a first detection optical unit for detecting a first image formed by light reflected from the object by the illumination of the slit-like shaped laser and reflected in a first direction substantially normal to a surface of the object, a second detection optical unit for detecting a second image formed by light reflected from the object by the illumination of the slit-like shaped laser and reflected in a second direction inclined to the normal direction to the surface of the object, an image signal processing unit which processes a signal outputted from the first detection optical unit and a signal outputted from the second detection optical unit, and an output unit which outputs information processed by the image signal processing unit.