To improve the detection precision of a recess or projection position of an inspected body by increasing discrimination from print contents of the inspected body when the recess or projection of the inspected body is detected as a step.

Laser lights from lighting systems 1 and 2 irradiate a specific area of the inspected body 3 and are reflected and made incident on a dichroic mirror 6. The dichroic mirror 6 separates the reflected light, which are imaged by imaging lenses 7 and 8, so that CCD sensors 9 and 10 read two kinds of image (pixel value). The read image information is sent to an image processing means. The image processing means adjusts the level of shading between a pixel of interest and its peripheral pixels in the image information and then perform a line drawing emphasizing process and a difference image process of the two kinds of image. In the difference image process, pixel values of the two kinds of image which are read and processed are compared to extract and compute only pixels having the different polarities at corresponding positions, thereby specifying the position of a step part on the inspected body 3.