In an image-forming device, a first roller and a second roller are arranged in a first direction, the first roller being disposed upstream of the second roller in the first direction. An endless belt spanned between the first roller and the second roller forms a straight plane extending in the first direction. The straight plane moves in the first direction when the endless belt is circularly moved. Photosensitive members are arranged in the first direction and face the straight plane. A transfer member is opposed to the first roller across the endless belt. A cleaning unit includes: a cleaning member opposed to the straight plane at an upstream of an upstream most photosensitive member in the first direction; and a treating member disposed upstream of the cleaning member in the first direction to treat residual toner collected by the cleaning member. A conveying path formed between the transfer member and a fixing member passes between the cleaning member and the treating member.