A surface of a work to be inspected is irradiated with an illumination unit for a coaxial incident illumination and an illumination unit for an oblique incident illumination driven to take its image by a camera at the same time. Each of the illumination units and comprises light sources emitting color lights R, G and B, respectively. One of the three kinds of light sources is lighted in the illumination unit and one or two of the light sources which are not lighted in the illumination unit are lighted in the illumination unit.
