An image forming apparatus of the present invention includes a developing unit for developing a latent image formed on an image carrier with a two-ingredient type developer, i.e., a toner and carrier mixture. A toner replenishing device replenishes toner stored in a toner storing portion to the developing unit. A carrier storing portion, storing a carrier therein, is constructed independently of the toner storing portion. The carrier is fed from the carrier storing portion to the developing unit by a toner conveying force available with the toner replenishing device.