An image forming apparatus includes first and second image forming units each including a charging device and a development device using a developer including a mixture of toner and carrier, a transfer device for serially transferring toner images onto a transfer medium, a replenishment device for replenishing a replenishing developer including a mixture of toner and carrier to each development device, and a discharge device for discharging the developer. The second image forming unit is disposed on a downstream side of the first image forming unit in a transfer medium travel direction. Each development device of the first and second image forming units is configured to recover a residual transfer toner remaining on each image bearing member. A weight percent of carrier in the replenishing developer to be replenished to the development device of the second image forming unit is larger than that of the first image forming unit.