An image forming apparatus of the present invention includes at least one process cartridge removably mounted on the apparatus body and including at least an image carrier (2) on which a toner image is to be formed and a cleaning device (13) configured to remove toner left on image transfer with a cleaning blade. A hole (69,44) for passing a light beam emitted from an optical writing unit (8) toward the image carrier therethrough is formed in part of the case bottom wall of the process cartridge higher in level than part of the case bottom wall below the cleaning blade.
