Image forming apparatus

An image forming apparatus comprising:

• an apparatus body;
• an image carrier on which a toner image is to be formed;
• a cleaning device constructed integrally with said image carrier and including a cleaning member configured to remove a residual toner left on said image carrier after transfer of the toner image;
• and
• at least one process cartridge removably mounted on said apparatus body and including a case bottom wall formed with a hole that allows a light beam emitted from an optical writing unit to be incident on said image carrier therethrough;
• wherein when said process cartridge is mounted on said apparatus body, said hole is positioned in a portion of said case bottom wall positioned at a higher level than a portion of said case bottom wall below said cleaning member.