PURPOSE: To make color discrimination accuracy higher by discriminating the colors of bottles in accordance with image information and classifying the bottles of specific colors and bottles of other colors in accordance with the result of the discrimination.

CONSTITUTION: The various densities of the colors of the glass bottles G transported by a conveyor belt 24 are detected by using an illuminance meter 33. The photodetection quantity of a CCD camera 34 is adjusted according to the various densities of the colors of the glass bottles G by driving a diaphragm mechanism 35 of this CCD camera 34. A personal computer 70 discriminates the colors of the bottles G in accordance with the image information of the glass bottles G taken by the CCD camera 34. The bottles G of the specific colors and the bottles G of other colors are classified by a classifying device 20 in accordance with the results of the discrimination. As a result, the color discrimination accuracy is made higher.