A toner supply container, detachably mountable to a main assembly of an image forming apparatus, for supplying toner to the main assembly of the image forming apparatus, the toner supply container includes a main body for accommodating the toner; a discharging opening for permitting discharging of the toner accommodated in the main body of the container; a container shutter member for opening and closing the discharging opening; a rotatable member rotatably supported by the main body of the container and having a drive transmitting portion for engaging with a rotational force transmitting means provided in the main assembly of the apparatus to transmit the rotational force to the rotational force transmitting means; a rotating force receiving portion for receiving the rotating force from the rotating force transmitting means through engagement with the rotating force transmitting means, wherein the container shutter member is given a force for opening and closing the discharge opening by the rotating force received by the rotating force receiving portion; wherein when the toner supply container is not mounted to the main assembly of the apparatus, the rotatable member is rotatable relative to the main assembly of the container between a first position and a second position away from the first position in a rotational direction of opening the container shutter member by a predetermined rotational angle; the rotatable member being provided with a contact portion which is contacted by the main assembly of the apparatus to direct the rotatable member to the second position when the drive transmitting portion and the rotating force transmitting means are engaged to mount the toner supply container to the main assembly of the apparatus.