An image forming device includes: a main casing; a retaining unit; a feed tray; and a pickup roller. The retaining unit retains a plurality of photosensitive drums juxtaposedly arrayed and spaced away from each other in an array direction. The retaining unit is movable in the array direction between a mounted position in which the retaining unit is mounted in the main casing and a pulled-out position in which the retaining unit is pulled out of the main casing. The feed tray is configured to accommodate a first transferred medium. The pickup roller is configured to pick up the first transferred medium accommodated in the feed tray. The pickup roller is arranged to overlap with the retaining unit in the array direction.