Developing apparatus, process cartridge, and image forming apparatus

An image forming apparatus, comprising:

• an image bearing member;
• a bottle configured to accommodate a developer of a single magnetic component;
• a pump unit configured to supply the developer with air from the bottle;
• and
• a developing apparatus configured to develop a latent image with the developer which is supplied by the pump, comprising:
• a developer bearing portion having a magnetic body that generates a magnetic force and is configured to bear the developer with a carrying force working in a substantially perpendicular direction to the magnetic force;
• and
• a developer accommodation portion having a supply opening to receive the developer supplied by the pump and a discharge opening to discharge the developer, the developer accommodation portion accommodating the developer supplied from the supply opening and discharging the developer through the discharge opening to the image bearing member, and configured to have no opening other than the supply opening and the discharge opening, with the developer accommodation portion having a space volume so that a spouting force does not exceed the carrying force by the developer bearing portion, the spouting force acting on the developer born by the developer bearing portion in a discharging direction of the developer from the discharge opening which is caused by an increasing of an inner pressure when the developer is supplied by the pump in a state where a predetermined amount of the developer is stored.