An image forming apparatus includes a photoconductive drum, a primary transfer belt, a secondary transfer counter roller, a secondary transfer roller, a bias control circuit, a belt cleaner, and a processor. The photoconductive drum forms a toner image. The primary transfer belt comes in contact with the photoconductive drum and receives the toner image from the photoconductive drum. The secondary transfer counter roller moves the primary transfer belt. The secondary transfer roller presses a printing medium against the primary transfer belt to transfer the toner image on the primary transfer belt to the printing medium. The bias control circuit applies a bias to the secondary transfer roller. The belt cleaner is in contact with the primary transfer belt and removes attached matters from the primary transfer belt. When a printing operation is interrupted, a cleaning operation can be executed to remove residuals on the primary transfer belt.