A developer supply container detachably mountable to a developer supply apparatus including a container body, for accommodating developer, including a discharge opening for permitting discharge of the developer therefrom, coupling device, disposed connectable to a coupling member of the developer supply apparatus, for rotating the container body, feeding device for feeding the developer toward the discharge opening in the container body by the rotation of the container body, and regulation device, disposed at a peripheral surface of the container body, for regulating mounting of the developer supply container on the basis of whether or not it is substantially fitted with a regulation member of the developer supply apparatus. After the developer supply container is set to the developer supply apparatus, the regulation device is capable of rotating the regulation member of the developer supply apparatus by a rotational force received by the coupling device while retaining engagement of the regulation device with the regulation member.