An image-forming/processing station forms images in a plurality of colors in a superposed manner, in units of individual colors, on an identical unrolled portion of a recording roll medium, in accordance with color image formation data. When the images in the plurality of colors are to be formed, a recording medium conveying unit reciproctes, a plurality of times, the identical unrolled portion of the recording roll medium to the image-forming/processing station, in accordance with formation of the image in the plurality colors, and conveys a recorded-on unrolled portion of the recording roll medium to a downstream side of the station when formation of the images in the plurality of colors is completed. A recording medium storing unit is provided on the downstream side of the station and temporarily stores the unrolled portion of the recording roll medium on which image formation in each color is to be performed. A recording medium discharging unit is provided on the downstream side of station means and discharges the unrolled portion of the recording roll medium on which image formation in each color has been performed. A switching unit is provided on the downstream side of the station, which can be switched between first and second positions, for guiding the unrolled portion of the recording roll medium toward the storing unit or the discharging unit.