Patent ID: 8260169

Claim:
A developer storing container detachably mounted to a mounting portion of a developing unit, said developer storing container comprising: a developer storing body that stores a developer therein and has a first opening and a tapered surface formed on said first opening, and a shutter member provided in said developer storing body so that said shutter member is movable along an inner surface of a wall of said developer storing body where said first opening is formed, said shutter member being capable of taking a closing position for closing said first opening and an opening position for opening said first opening, wherein said shutter member comprises a first seal member formed of a resilient material, said first seal member including a seal portion provided at least along said first opening in a state where said shutter member is in said closing position, and an extending portion extending from said seal portion in an opening direction in which said shutter member opens said first opening, and wherein a distance from an end portion of said first opening in said opening direction to an end of said extending portion in a state where said shutter member is in said closing position is longer than a distance moved by an end portion in said opening direction of an exposable portion of said first seal member when said shutter member moves from said closing position to said opening position, said exposable portion being defined as a portion of said first seal member exposed via said first opening in a state where said shutter member is in said closing position, and further wherein in a state where said developer storing container is mounted to said mounting portion, said tapered surface of said developer storing body contacts a second seal member provided on said mounting portion.