PURPOSE: To make a conventional device suitable for color reproduction as well by dividing a rotary disk into 3×N segments provided with filters for one of three primary colors respectively.

CONSTITUTION: The rotary disk 10 provided with plural color filters 16-18 is arranged between a light source 12 for irradiating an optical gate 15 and a medium 13 for guiding light from the light source 12 to the optical gate 15. The rotary disk is divided into 3×N segments provided with the filters for one of three primary colors respectively. Thus, the color reproduction can be attained without adopting any special step in an optical printing head 14. Further, the spectral distribution of the light from a light source used and the spectral sensitivity characteristic of a photosensitive material can be taken in the structure of the filters 16-18.