An image forming device includes a housing; a conveying belt, and a retaining member. The retaining member retains image bearing members that juxtaposed with and spaced apart from one another. The retaining member is slidingly movable relative to the housing in a direction that the image bearing members are juxtaposed. The retaining member retains the image bearing members to confront the conveying belt. The image bearing members and the conveying belt are arranged in a reference direction. The retaining member includes a cleaning member that removes residual developing agent from the conveying belt, and a guide unit that guides the recording medium to the conveying belt. The guide unit is located on the image bearing member side and the cleaning member is located on the conveying belt side. At least part of the guide unit overlaps at least part of the cleaning member when projected in the reference direction.