IMAGE FORMING APPARATUS

An image forming apparatus includes an image bearer, a rotation shaft, a developing device, and a supply portion. The developing device includes a developing device main portion that rotates around the rotation shaft between a developing position and a retracted position and includes a developer, a developer bearer to face or be away from the image bearer depending on whether the developing device main portion is at the developing position or the retracted position, a replenishment portion having a replenishment port with an opposite surface formed by an arc drawn around the rotation shaft to replenish the developer, and a non-rotating portion. The supply portion has a supply port with an opposite surface formed by an arc drawn around the rotation shaft and facing the opposite surface of the replenishment port. The supply port communicates the replenishment port and supplies the developer to the developing device through the replenishment port.