An electrophotographic image forming apparatus for forming an image on a recording material, the electrophotographic image forming apparatus includes a drum cartridge including an electrophotographic photosensitive member drum; a developing cartridge including a developing roller for developing an electrostatic latent image formed on the electrophotographic photosensitive drum using a developer; a supporting member movable between an inside position and a retracted position in the state that supporting member supports the drum cartridge and the developing cartridge, wherein the inside position is inside the main assembly of the apparatus, and the retracted position is retracted from the main assembly of the apparatus; wherein the supporting member supports the drum cartridge and the developing cartridge independently demountably therefrom, wherein mounting and demounting directions of the drum cartridge relative to the supporting member and mounting and demounting directions of the developing cartridge are different from each other.