A belt driving controller is disclosed. The belt driving controller executes driving control of a belt that is wound around plural sustaining rollers by controlling a driving sustaining roller that transmits driving force to the belt. The belt driving controller executes the driving control of the belt by controlling the driving sustaining roller so that a moving velocity fluctuation of the belt caused by a PLD (pitch line distance) fluctuation in the belt circumference direction becomes small, based on rotation information of rotation angle displacement or rotation angle velocities of two sustaining rollers in the plural sustaining rollers, in which two sustaining rollers, the diameters thereof are different from each other and/or the degrees to which the PLDs of parts of the belt which wind around the two sustaining rollers influence the belt moving velocity and the rotation angle velocities of the two sustaining rollers are different from each other.