A developing device, includes a first storage chamber that stores developer; a first conveyor that is disposed in the first storage chamber and conveys developer; a developer supporter that is disposed so as to face an image supporter, supports developer conveyed from the first conveyor, and conveys the supported developer to a developing position where an electrostatic latent image formed on the image supporter is developed; a second storage chamber that stores developer conveyed via the developing position and communicates with the first storage chamber at a confluent opening; a second conveyor that is disposed in the second storage chamber and conveys developer conveyed via the developing position toward the confluent opening; and a third storage chamber that stores developer overflowing in a case where an amount of developer in the second storage chamber becomes a predetermined amount or more.