An image formation apparatus is provided with a photosensitive drum, an optical
writing device which writes an image on the outer surface of the photosensitive
drum, a developing device which develops the image using toner an intermediate
transfer belt onto which the toner image on the photosensitive drum is transferred,
a rotation angle detection unit which detects the rotation angle of the photosensitive
drum, an eccentric detection unit which detects the amount eccentricity of the
photosensitive drum from the rotary axis of the photosensitive drum, and a correction
unit which, obtains eccentricity of the photosensitive drum based on the amount
eccentricity, the rotation angle and the radius of the photosensitive drum, and
corrects a distortion and a color offset in the toner image based on the obtained eccentricity.