There is provided a developing unit, including: a body defining a developing chamber and a developer accommodating chamber, and a developer delivery member. The body includes a sliding portion, a restoring portion and a colliding portion at the developer accommodating chamber. The developer delivery member includes an elastic member configured to be made a sliding contact with the sliding portion while being curved elastically, configured to be restored elastically at the restoring portion, and configured to collide with the colliding portion. The developer delivery member is configured so that, the elastic member which has been elastically restored at the restoring portion is collided with the colliding portion to generate an air flow and to deliver the developer in the developer accommodating chamber toward the connection port.