An electrophotographic image forming apparatus includes an electrophotographic photosensitive drum; a developing 
cartridge including a developing roller for developing a 
latent image formed on the drum, a developer accommodating portion for accommodating a developer to be used by the developing roller to develop the electrostatic 
latent image, and a developing roller 
shutter movable between a protecting position for covering a part of a 
peripheral surface of the developing roller and a retracted position, retracted from the protecting position, for 
exposure the part of the 
peripheral surface of the developing roller, wherein the developing 
cartridge is detachably mountable to a main 
assembly of the apparatus; a 
cartridge supporting member movable, while detachably mounting the developing cartridge, between an inside position which is inside of the main 
assembly of the apparatus to 
Mount the developing cartridge to the main 
assembly of the apparatus and an outside position which is outside of the main assembly of the apparatus to remove the developing cartridge from the main assembly of the apparatus; a force receiving portion, provided on the developing cartridge, for receiving a force for moving the developing roller 
shutter from the protecting position to the retracted position; and a force applying portion provided in the main assembly of the apparatus, wherein when the cartridge supporting member is moved from the outside position to the inside position, the force receiving portion contacts to the force applying portion to move the cartridge supporting member from the outside position to the inside position, in interrelation with which the force receiving portion contacted to the force applying portion receives the force from the force applying portion, thus moving the developing roller 
shutter from the protecting position to the retracted position.