PURPOSE: To realize a compact design as a whole and to perform a color projection with a simple operation for a color image forming device, by setting a switch type color seprating filter device to a short-focus lens array through which an original picture is formed into an image and projected to a recording medium.

CONSTITUTION: A switch type color separating filter device is set under a short- focus lens array 7. The device 8 contains color seprating filters 81B, 81G and 81R which are attached and supported to plural support members 83W85. These support members can turn concentrically and independently centering on the shafts parallel to each other and provided at the position near the array 7. The members 83W85 are selectively turned for each color separating copy, and a prescribed color separating filter is put into an image forming/projecting optical path L in a switching way.