PURPOSE: To prevent the generation of a void, bleeding of an image and fog in a copy image by setting so that an electric field for going to the reverse direction becomes larger than an electric field for going to a member to be electrified from a discharge wire, and also, providing a ventilation use opening part on the back side of a discharge shield.

CONSTITUTION: By setting so that an electric field for going to the reverse direction becomes larger than an electric field for going to a member to be electrified 4 from a discharge wire 20, an ion wind (an air flow generated by an ion flow which follows up a corona discharge) which follows up a corona discharge goes to the direction reverse to the member to be electrified 4. Also, by providing a ventilation use opening part 26 on the back side of a discharge shield 16, the air flow is emitted to the direction reverse to the member to be electrified 4 through this opening part 26, and it is prevented that a product which follows up the corona discharge adheres to the member to be electrified. In such a way, the generation of deletion is prevented even under the environment of high humidity without increasing remarkably the capacity of a fan.