An image forming apparatus calculates the amount of staying toner based on the amount of drive of the developer roller and the amount of toner consumed for a print job performed. When the amount of staying toner exceeds a threshold, the toner is discharged. The threshold used upon completion of image stabilization is larger than that used upon completion of a print job. Even when performing image stabilization temporarily increases the amount of staying toner in the developing device, immediate toner discharge based on that condition is prevented. Thus, toner consumption can be minimized.