The present invention has been made to provide an image forming apparatus capable of suppressing reverse charging caused by a transfer electric field to thereby suppressing memory image level to a lower level without providing a charge eliminating unit. In am image forming apparatus according to the present invention, a controller 191 increases and decreases a transfer current from a transfer roller 23 in accordance with the rise and fall of setting values to be set of the background potential of a photoconductor drum 10 and developing bias potential of a developing unit 18. By increasing and decreasing the setting value of the transfer current as described above, it is possible to suppress memory image level (residual image level) that can be caused when the setting values of the background potential of the photoconductor drum 10 and developing bias potential are decreased. In the case where the setting values of the background potential of the photoconductor drum 10 and developing bias potential are set back, the transfer current is also set back, so that it is possible to keep the memory image level at a favorable level.