A belt driving device is provided and includes a plurality of rollers
including a driving roller. A belt is configured to be tensioned by the
plurality of rollers, and to be driven by the driving roller. The driving
roller is arranged adjacent to where an outside body contacts an outer
surface of the belt. A pair of fluctuation absorbing members may be
configured to absorb tensional fluctuation of the belt at an upstream and
a downstream of a cleaning member in a direction which the belt is
driven. A detecting means may be utilized to detect a driving load of one
of the driving roller and the outside roller and a controller is
configured to drive another roller of the driving roller and the outside
roller based on the driving load detected by the detecting means. An
outside roller may be configured to contact an outer surface of the belt
and to be driven by a second motor; a controller configured to control
the second motor by a less loop gain than a loop gain to control the
first motor.