PURPOSE: To improve the utilization efficiency of light, and to obtain an exposing device at low cost by radiating an electromagnetic wave to a phosphor from one piece of electromagnetic wave radiation source, emitting a light beam of wavelength of a prescribed area, and exposing a photosensitive recording medium through a light shielding property image.

CONSTITUTION: A photosensitive drum 6 is exposed 10 successively by each color of cyan, magenta and yellow, and a light shielding property image 13 is formed. Its light shielding property image 13 is transferred to a light transmission property member 16 by a transfer roller 17. Subsequently, the light transmission property member 16 and photosensitive recording paper 21 are put together, and exposed by an exposing part 4. In this regard, as for the photosensitive recording paper 21, a microcapsule containing a coloring substance is applied. Also,the exposing part 4 emits light beams different in prescribed area from plural phosphorus 24 by radiating ultraviolet rays from one piece of electromagnetic wave radiation source 22, and moves and places selectively its phosphor 24 in a radiation path of ultraviolet rays. Next, the photosensitive recording paper 21 which is exposed by each color is brought to coloring by a pressure developing part 15. Accordingly, since a light beam of prescribed wavelength is emitted from each phosphor, an exposing device can be obtained at low cost without using an expensive interference filter.