PURPOSE: To excellently reproduce a black color by radiating four kinds of light beams whose wavelengths are different one another to a color photosensitive material where a microcapsule containing yellow, magenta, cyanogen and black color image forming substance is applied on a supporting body and controlling the coloring of yellow, magenta, cyanogen and black.

CONSTITUTION: The photosensitive pressure sensitive heat developing color photosensitive material having sensitivities which are respectively effective to spots near the wavelengths of 425nm, 532nm, 650nm and 850nm is used. Image light projected from a light source 250 for exposure passes through an optical path 264 and is reflected by a polygon mirror 270. And it passes through an fθ lens 280 and is reflected by a mirror 290, then it reaches the photosensitive material S. And the polygon mirror 270 rotates centering around a shaft 271, so that the image light scans and exposes the photosensitive material S. Since the photosensitive material is exposed with the light beams having four kinds of wavelengths corresponding to cyanogen, magenta, yellow and black, the intensity of the respective light beams can independently modulated, so that the black color can be excellently reproduced.