PURPOSE:To almost perfectly remove a residual developer, by applying a charge to a developer remaining on a magnetic latent image carrier body, and thereafter, removing the residual developer from the magnetic latent image carrier body by electrostatic force. CONSTITUTION:The developer 12 remaining a magnetic latent image carrier body 1 after transfer receives the desired charge by discharge from a pre- cleaning corotron 8A arranged close to the feed path of the carrier body 1 and bias voltage is applied to the bias roll 13 arranged downstream from the pre- cleaning corotron 8A by a high voltage power source 14. An electrolytic field of the desired polarity and intensity is generated between the bias roll 13 and the opposed roll 15 arranged in opposed relation thereto. The residual developer 12 on the carrier body 1 is detached from the carrier body 1 by electrostatic force of the electrostatic field affecting the charge possessed by the residual developer 12 when passed between the bias roll 13 and the opposed roll 15 and adhered to the bias roll 13. By the above mentioned mechanism, the cleaning of the carrier body 1 is achieved.