An image forming apparatus includes a rotatable photosensitive member, a charging member, an applying device, an irradiation device, and a controller. The charging member contacts the photosensitive member to charge the photosensitive member. The applying device applies a direct-current voltage to the charging member. The irradiation device irradiates with light an upstream charging gap located upstream of a contact portion between the photosensitive member and the charging member in a rotation direction of the photosensitive member. The controller controls the irradiation device to irradiate with a first light amount when the photosensitive member rotates at a first speed, and to irradiate with a second light amount that is larger than the first light amount when the photosensitive member rotates at a second speed that is lower than the first speed.