An image forming apparatus includes a photosensitive member configured to form a toner image thereon, a corona charger located opposite the photosensitive member and including a discharging wire and a grid electrode, a bias applying unit configured to apply a bias to the corona charger, a cleaning unit configured to perform cleaning processing by sliding in a longitudinal direction of the grid electrode to rub an inner surface of the grid electrode, and an execution unit configured to execute a cleaning mode for performing the cleaning processing by the cleaning unit while applying a bias of a polarity equal to a normal charging polarity of toner to the grid electrode by the bias applying unit.