In an image forming apparatus including a door 10 openable with respect to a main assembly of the image forming apparatus, a drum cartridge 8 detachably mountable to the image forming apparatus main assembly, and detachably mountable developing cartridges 4k-4y provided above the drum cartridge 8, wherein the door 10 includes a positioning urging portion 26 contacting the developing cartridges in a state in which the door 10 is closed, the door 10 includes drum cartridge mounting and demounting guides 28R and 28L for regulating the drum cartridge 8 so as to pass along a non-interference path with the positioning urging portion 26 in contact to the drum cartridge 8 when the drum cartridge 8 is demounted from the image forming apparatus.