DEVELOPER SUPPLY CARTRIDGE, PROCESS CARTRIDGE, AND IMAGE FORMING APPARATUS

PROBLEM TO BE SOLVED: To provide a developer supply cartridge including a supply opening that opens upon completion of attachment irrespective of an opening/closing state of the supply opening.SOLUTION: A developer supply cartridge includes: a developer storage unit 40; a shutter unit 49 that can be moved between a closing position to close a supply opening 43 of the storage unit 40 and an opening position to open the supply opening 43; and a moving unit 52 that can be moved between a first position to locate the shutter unit 49 at the closing position and a second position to locate the shutter unit 49 at the opening position, is moved in association with the movement of the developer supply cartridge due to engagement of the developer supply cartridge with an engaging part provided on an apparatus body side during the movement of the developer supply cartridge to a predetermined attachment position of the apparatus body, and is moved due to the engagement with the engaging part at the first position and is located at the second position when the developer supply cartridge reaches the attachment position. When the developer supply cartridge is attached to an apparatus body and the moving unit 52 is at the second position, the moving unit 52 performs avoidance operation to avoid the movement of the developer supply cartridge to the first position due to the engagement with the engaging part.