An image forming apparatus includes an image bearing member on which an electrostatic image is formed, a developing unit to develop the electrostatic image, a driving unit, a driving gear to drive the driving unit, and a toner replenishing container to attach to an attaching portion of the image forming apparatus and to accommodate the toner to replenish to the developing unit. In addition, a door opens and closes the attaching portion, a first mechanism changes an open/close state of the door, and a second mechanism changes an input state of the driving force to a shaft of the first mechanism.