A driving apparatus with a power disconnecting part for disconnecting power transmitted to an image fixing unit while an image formed on an image transfer belt is cleaned when a paper jam occurs, and an image forming apparatus and method for performing the same. The image forming apparatus includes a driving motor, a belt unit driving part having a belt driving gear connected to the driving motor to drive an image belt, an image fixing unit driving part having an image fixing gear for driving an image fixing roller for fixing a toner image onto a recording medium, a power disconnecting part for transmitting the power of the driving motor of the belt unit driving part to the image fixing unit driving part or for disconnecting the power transmission of the driving motor from the image fixing unit driving part, and a power disconnection actuating part for actuating the power disconnecting part.