Process cartridge and image forming apparatus

An image forming apparatus for forming an image on a recording material, comprising:

• a process cartridge detachably mountable to a main assembly of an image forming apparatus, wherein said process cartridge includes:
• an image bearing member unit including an image bearing member rotatably provided;
• a developing unit including a developer carrying member for carrying a developer;
• a shaft provided in one of said image bearing member unit and said developing unit at an end portion of said process cartridge with respect to an axial direction of said image bearing member;
• and
• an opening, provided in the other unit at the end portion, engaged with said shaft to permit movement of said developing unit relative to said image bearing member unit,
• wherein said opening defines a first contact portion, in a state in which said process cartridge is mounted to the main assembly, contacting said shaft to permit rotational movement of said developing unit relative to said image bearing member unit, and defines a second contact portion which receives normal reaction from said shaft in a direction inclined with respect to a direction of normal reaction received from said shaft by the first contact portion and which moves, when the second contact portion contacts said shaft in a state in which said process cartridge is mounted to the main assembly and does not receive a driving force from the main assembly, said developing unit so that said shaft and the first contact portion are contacted to each other;
• and
• conveying means for conveying the recording material.