Abstract: An image forming apparatus includes an image carrying member for carrying an image, a developing unit for developing an electrostatic image on the image carrying member, and a toner storage unit for storing the toners and replenishing the toners to the developing unit. In the image forming apparatus, a residual quantity of the toners within the toner storage unit is detected, and a quantity of toners substantially replenished to the developing unit from the toner storage unit is integrated. When a deficiency of the toner residual quantity is detected during a consecutive image forming operation, there is stopped and inhibited the image forming operation when an integrated value of the replenishing toner quantity reaches a predetermined value since the deficiency of the toner residual quantity was detected.