When a copy sheet jams in the process of image formation in an image forming machine with a detachable unit having at least an image carrier device, it is necessary to detach the unit to remove the sheet in the state the image carrier device is charged with electric charge. In such a case, when the unit is detached and again attached, spark discharging may occur inducing noise upon a contact of an electrically conductive shaft of the image carrier device to the ground conductor provided in an image forming machine body and malfunction is induced in an initializing program. The image forming machine of the present invention prevents the occurrence of such a problem. Guide grooves are provided to base frames of the image forming machine to guide both end parts of the electrically conductive shaft of the image carrier device to position the unit in place, and a charge eliminating member is provided upstream from the position for allowing the electric charge accumulated on the image carrier device to be corona-discharged by way of the conductive shaft thereof to remove the charge accumulated thereon.