A toner supply container is detachably mountable to an image forming apparatus and includes a container body for containing toner; a shutter for closing and opening an opening, which is provided in the container body; a rotatable member; and a projection. The shutter includes a first gear portion for meshing engagement with a first gear member, which is provided in the image forming apparatus. The rotatable member, which is rotatable relative to the container body, produces a driving force for opening and closing the shutter. The rotatable member includes a second gear portion for meshing engagement with a second gear member, which is provided in the image forming apparatus. The first gear member and second gear member are rotatable together. The projection, which is provided on the rotatable member, receives a force for pre-rotating the rotatable member through a predetermined angle in a direction of opening the shutter, from the image forming apparatus in response to a mounting operation of the toner supply container to the image forming apparatus. The rotatable member is rotatable through a predetermined angle in a direction of closing the shutter from a position at which the second gear portion is in meshing engagement with the first gear member. The projection enables disengagement between the first gear portion and the second gear member so as to substantially prevent the second gear portion from rotating the second gear member in a dismounting operation of the toner supply container from the image forming apparatus.