A developer container has a main part accommodating a developer therein and is detachably attached to an image forming apparatus. The developer container comprises a rotation unit which is rotatable to the developer container main part and having an outlet to discharge developer from the developer container, a shutter provided on the rotation unit to open and close the outlet by rotation of the rotation unit, and an engagement unit provided on the periphery side portion of the rotation unit in order to prevent rotation of the rotation unit when attached to the image forming apparatus.