A cartridge detachably mountable to a main body of an image forming apparatus, includes a developing frame, a developer carrying member provided in the developer frame and adapted to hold and carry developer, a developer containing container for containing the developer and for supplying the developer to the developer frame, a seal member for unsealably sealing an opening portion through which the developer is supplied from the developer containing container to the developing frame, a rotary member for supplying the developer toward the developer carrying member, a first drive transmitting device for effecting drive transmission between the developer carrying member and the rotary member, and a second drive transmitting device for transmitting the driving to the seal member to unseal the seal member.