A developer supply container detachably mountable to a developer receiving apparatus including a driving gear and settable in the developer receiving apparatus by a setting operation including at least a manual rotation toward a developer supply position where a developer is supplied from said developer supply container to the developer receiving apparatus in a setting direction, said developer supply container comprising: a container body having an inner space configured to contain the developer; an opening provided in a peripheral portion of said developer supply container at such a position that the rotation of said developer supply container in the setting direction changes a direction toward which said opening faces from upward to sideward, said opening being configured to permit discharge of the developer in said container body to the developer receiving apparatus; a developer feeding device configured and positioned to feed the developer in said container body toward said opening by rotation thereof relative to said container body when said developer supply container is positioned at the developer supply position; characterised in further comprising a regulating portion (1g, 100) configured and positioned to regulate a mounting attitude of said developer supply container into the developer receiving apparatus so that said opening is oriented upward; and a driving system (5, 6; 1000) configured and positioned to receive a rotating force from the driving gear rotating in a direction opposite to the setting direction to maintain said developer supply container at the developer supply position by urging said developer supply container in the setting direction, and to transmit the rotating force to said developer feeding device so that said developer feeding device is rotated in a direction opposite to the setting direction and a peripheral movement of said developer feeding device is upward adjacent to said opening which is oriented sideward. a container body having an inner space configured to contain the developer; an opening provided in a peripheral portion of said developer supply container at such a position that the rotation of said developer supply container in the setting direction changes a direction toward which said opening faces from upward to sideward, said opening being configured to permit discharge of the developer in said container body to the developer receiving apparatus; a developer feeding device configured and positioned to feed the developer in said container body toward said opening by rotation thereof relative to said container body when said developer supply container is positioned at the developer supply position; characterised in further comprising a regulating portion (1g, 100) configured and positioned to regulate a mounting attitude of said developer supply container into the developer receiving apparatus so that said opening is oriented upward; and a driving system (5, 6; 1000) configured and positioned to receive a rotating force from the driving gear rotating in a direction opposite to the setting direction to maintain said developer supply container at the developer supply position by urging said developer supply container in the setting direction, and to transmit the rotating force to said developer feeding device so that said developer feeding device is rotated in a direction opposite to the setting direction and a peripheral movement of said developer feeding device is upward adjacent to said opening which is oriented sideward.