To provide an image forming apparatus which implements a means of applying a cleaning bias having the polarity opposite to a developer to a transfer part as a cleaning means for a transfer body, the image forming apparatus being equipped with the transfer body cleaning means which displays excellent cleaning performance even when the electrostatic charge quantity of the developer is high, when the amount of a developer to be cleaned is large, or in low-temperature and low-humidity environment and damages neither an image carrier nor the transfer body.

The image forming apparatus which has an image carrier which has a toner image formed on its surface, the transfer boy whose surface moves facing the image carrier, and a transfer means of applying a transfer bias between the image carrier and transfer body, and cleans the transfer body by applying a cleaning bias for reversely transferring a developer sticking on the transfer body to the image carrier to the transfer means is characterized in that the cleaning time is made variable depending upon specified conditions.