The present invention provides an image-forming device having a developer-carrying member, an image-carrying member, a belt, and a cleaning unit. The developer-carrying member has an outer surface including a thin layer forming region for carrying a thin layer of developer. The thin layer forming region has a first width in a widthwise direction. The thin layer forming region includes an effective image forming region used for forming an image on a recording medium. The image-carrying member has a surface on which an electrostatic latent image based on the image is formed and developed into a developer image by the developer carried on the effective image forming region. The belt is configured to circulate in a moving direction orthogonal to the widthwise direction and transfer the developer image onto the recording medium. The belt has an outer surface including a cleanable region having a second width in the widthwise direction. The cleaning unit cleans the developer on the cleanable region. The second width is greater than the first width. The cleanable region is placed with respect to the thin layer forming region so that each widthwise end of the second width is positioned outside of each widthwise end of the first width in the widthwise direction.