To provide an image forming apparatus in which the surface of a photoreceptor drum can be reliably cleaned by using toner containing an abrasive from a developing device without unnecessarily wasting the toner while requiring no additional time other than for forming an image.

When the width of a sheet P supplied is smaller than the width of a sheet Pmax having the allowable maximum width, an electrostatic latent image X corresponding to the sheet P is formed on the surface of the photoreceptor drum 1 by an exposure device 3. An auxiliary latent image Y is formed in a specified region during the intermediate period of paper feeding, the region being the outer region with respect to the end of the region corresponding to the sheet P of the electrostatic latent image X, outside the extended lines of the sides X1 in the electrostatic latent image X and inside the extended lines of the sides Pmax1 in the sheet Pmax having the allowable maximum width. Then, the toner is deposited on the electrostatic latent image X and on the auxiliary latent image Y by the developing device 4 to form a toner developed image X' and an auxiliary developed image Y'.