A corona charger is provided with a back plate which defines a first space which surrounds a discharge electrode while opening a side that the discharge electrode faces an image carrier. The back plate is formed with a first opening. A storage has a second space which stores waste toner generated in the image forming apparatus. The storage is formed with a second opening. A filter causes ozone to pass through but blocks toner. The filter is disposed between the corona charger and the second space. The first space and the second space are communicated by way of the first opening and the second opening.