PURPOSE: To simplify the assembling and adjustment of a device by providing a light color discriminating sensor discriminating the color of light irradiated to a photoelectric converting element array, and synchronizing the changeover of plural filters different in spectral characteristic with the original reading scanning of the photoelectric converting element array based on the discriminated result of the color of light.

CONSTITUTION: When a reflected light of a read part 11 of a color original 2 is incident to the photoelectric converting element array 4 via a red filter 7R of a filter ring 7 by the color light discriminating sensor 8 is informed, a read scanning instruction is outputted to the array 4. The optical signal outputted through the reading scanning of the photoelectric converting element array 4 is stored in a reading red light storage circuit 5d of a storage circuit 5. Similarly, a control circuit 1 outputs a read scanning instruction every time a reflected light of the read part 11 iradiates the photoelectric converting element array 4 via a green filter 7G and a blue filter 7B and the corresponding optical signal is stored respectively in a green light storage circuit 5e and a read blue light storage circuit 5f. An arithmetic circuit 6 corrects the optical signal stored in the storage circuit 5 and outputs the optical signal corresponding to plural gradations.