PURPOSE: To obtain a magnetic brush cleaner having an always stable cleaning effect, by applying AC bias voltage in a prescribed range to the magnetic brush.

CONSTITUTION: A magnetic brush cleaner 5 forms a magnetic toner brush for removing the residual toner by rubbing the surface of a photosensitive drum 1, and AC bias voltage having 500W3,000V and 200W1,000Hz range is applied to the cleaning sleeve 8 of the cleaner 5 from a power supply 9, thus permitting the toner remaining on the drum 1 to be made easily separable by electrostatic action corresponding to this bias voltage, and the magnetic brush cleaner to have an always stable cleaning effect.