developer supply cartridge, detachably mountable in a mounting direction to a developer receiving cartridge being detachably provided in an image forming apparatus for supplying developer to said developer receiving cartridge, said developer supply cartridge comprising: a container body having an inner space for containing developer and a discharge opening for permitting discharge of the developer from said container body; and a shutter for opening and closing said discharge opening by rotation about a rotation centre thereof; the shutter is characterized in that it includes a plurality of sets of leaf-like portions having a hole for opening said discharge opening and leaf-like portions having no hole for closing said discharge opening, said leaf-like portions for opening and said leaf-like portions for closing being disposed alternately in a rotational direction of said shutter, wherein in the opening position of the shutter a hole is aligned with the discharge opening thereby creating an unblocked passage between the developer supply cartridge and the developer receiving cartridge, and a plurality of recesses which are disposed between adjacent ones of said leaf-like portions, and said leaf-like portions each having respective surfaces which are effective to rotate said shutter in two rotational directions, wherein when said developer supply cartridge is mounted to the developer receiving cartridge in the image forming apparatus, two of said recesses are at such positions that they are engageable with first and second pins (19b, 19c) arranged consecutively in said mounting direction on the developer receiving cartridge respectively, and one of said two recesses is capable of being used in an opening movement and a closing movement of said shutter, and the other is capable of being used in the closing movement of said shutter. a container body having an inner space for containing developer and a discharge opening for permitting discharge of the developer from said container body; and a shutter for opening and closing said discharge opening by rotation about a rotation centre thereof; the shutter is characterized in that it includes a plurality of sets of leaf-like portions having a hole for opening said discharge opening and leaf-like portions having no hole for closing said discharge opening, said leaf-like portions for opening and said leaf-like portions for closing being disposed alternately in a rotational direction of said shutter, wherein in the opening position of the shutter a hole is aligned with the discharge opening thereby creating an unblocked passage between the developer supply cartridge and the developer receiving cartridge, and a plurality of recesses which are disposed between adjacent ones of said leaf-like portions, and said leaf-like portions each having respective surfaces which are effective to rotate said shutter in two rotational directions, wherein when said developer supply cartridge is mounted to the developer receiving cartridge in the image forming apparatus, two of said recesses are at such positions that they are engageable with first and second pins (19b, 19c) arranged consecutively in said mounting direction on the developer receiving cartridge respectively, and one of said two recesses is capable of being used in an opening movement and a closing movement of said shutter, and the other is capable of being used in the closing movement of said shutter.