An image forming apparatus includes a rotatable photosensitive member, an image forming portion, a cleaning device, and a controller. The cleaning device includes a blade, a rotatable brush, and an applying portion. The controller controls the applying portion so as to apply a bias to the brush so that a potential of the brush has a polarity opposite to a normal charge polarity of toner. When a tensile strength of the brush is A (cn/dtex), a thickness of the brush is B (denier), a bristle density of the brush is C (kF/inch2), a length of the brush is D (mm), and an elastic deformation rate of the surface of the photosensitive member is E (%), the following relationships are satisfied: 48(%)≤E≤60(%), and 400≤{A×B2×C/D2}≤20408.