A transfer belt device includes an endless transfer belt that is tightly stretched by a plurality of rollers and forms a transport path where a recording medium or a developer image is transported facing a monochrome image bearing member and a plurality of color image bearing members arranged in parallel along a fixed direction. In the apparatus, a first transfer unit having a first linking member in which a monochrome-image transfer member is supported that transfers a developer image formed on the monochrome image bearing member onto a recording medium or an outer peripheral surface of the belt, and a second transfer unit having a second linking member in which a plurality of color-image transfer members are supported that transfer developer images formed on the respective color image bearing members onto a recording medium or an outer peripheral surface of the belt, are linked via the first and second linking members.