An image forming apparatus includes an image carrier; an exposure unit configured to form an electrostatic latent image on the image carrier; a developing unit including a toner containing unit configured to accommodate a predetermined amount of toner, a toner supply unit configured to supply replenishment toner into the toner containing unit, a stirring unit configured to stir the toner to impart electric charge to the toner, a toner carrying member configured to carry the toner charged by the stirring unit, and a bias applying unit configured to apply a developing bias to the toner carrying member to develop the electrostatic latent image formed on the image carrier with the toner carried by the toner carrying member; a density sensor configured to detect a density of a toner pattern developed by the developing unit; and a control unit configured to control an amount of the toner supplied to the toner containing unit.