A process cartridge detachably mountable to a main assembly of an apparatus, includes a drum, a developing member, a cartridge frame including a developer accommodating portion, a first light guide adjacent one end of the cartridge frame and a leading end with respect to a cartridge mounting direction and including a light entrance portion opposed to an emitting portion to receive detecting light when the process cartridge is mounted to the main assembly and guiding the detecting light to cross with a developer accommodating space in the developer accommodating container, a second light guide adjacent the one end and the leading end, and including a light exit portion and directing, the detecting light having passed through the developer accommodating space to the light receiving portion, and a memory member communicatable with the main assembly and adjacent the one end o and the leading and including a cartridge electrical contact.