A parallel circuit of a capacitor and a varistor is connected between a ground and an aluminum cap of a photosensitive drum having a photoconductor sheet wound on a surface of an aluminum drum. The capacitor is charged by a charger. A developer roll connected to a bias voltage supply is provided with a retraction mechanism and is controlled so that the developer roll is separated from the drum mechanically upon start of operation of a recording apparatus until a potential of the cap is increased to a predetermined value and a developing agent layer does not come into contact with the cap. Alternatively to retraction of the developing roll, the developing roll may be stopped to control a height of bristle of developing agent or a bias voltage of the developer may be reversed.