Abstract: An image forming apparatus includes a developer container to and from which the replenishment container is attachable and detachable and which includes an accommodating portion that accommodates developer and a replenishment port, an agitation, an opening/closing member configured to be movable between a closed position and an open position, a drive source for driving the agitation member, and a control portion configured to control the drive source, wherein the apparatus is configured such that image formation is not possible when the opening/closing member is at the open position, and the agitation member is capable of driving in a case where the opening/closing member is at the open position.