An image forming apparatus includes a photoreceptor and an exposure device. The exposure device is configured to expose a surface of the photoreceptor and to form an electrostatic latent image. The exposure device includes a light source, a polygon mirror and a polygon motor. The light source is configured to emit a beam. The polygon mirror is configured to deflect the beam emitted from the light source. The polygon motor is configured to rotate the polygon mirror. The polygon motor is rotated at least temporarily when an aging mode to remove moisture from the surface of the photoreceptor is executed.