To provide a developer replenishing device capable of reducing the quantity of toner sticking to and remaining on the inwall of a toner container.

A ring gear 5 is provided in a part on the side of the outflow port 2 of a toner bottle 1 and engaged with a driving gear 7 attached to the output shaft of an electric motor 6. The driving gear 7 is structured to lack a total of four teeth at intervals of an angle of 90°, out of a series of teeth 7a. Then, vibration is imparted by the lacked parts 7b, during the rotation of the toner bottle 1 and the falling off of the toner stuck on the inwall of the bottle 1 is accelerated by the vibration.