Abstract: When a photoreceptor provided in an image forming apparatus is electrified for image formation, the output of a charger starts with a different value from a predetermined value and it is controlled to gradually match up to the predetermined value. It is also controlled in a way to start with a lower value than a predetermined value corresponding to the time a charger suspended its operation and gradually match up to the predetermined time. Such control is carried out by controlling grid voltage which flows into grid electrode disposed between a photoreceptor and wire electrode provided for discharging.