A cartridge removably mountable to a main assembly of an electrophotographic image forming apparatus includes a developing member, a developer accommodating portion, a locking portion to engage a locking portion of the main assembly of the apparatus to prevent the cartridge from disengaging from the main assembly after mounting of the cartridge, a grip to be gripped by an operator when the cartridge is mounted to the main assembly, and a releasing portion to move the locking portion of the cartridge in interrelation with a movement of the grip which is moved when the operator grips the grip to disengage the cartridge from the main assembly of the apparatus. The locking between the locking portion of the cartridge and the locking portion of the main assembly is released by the movement of the locking portion of the cartridge.