To prevent the deterioration of toner such as the occurrence of rough particles, to reduce the power consumption of a motor, and also, to prolong the lives of the motor and a gear, etc., by optimizing a time for driving a stirring/carrying member in a toner cartridge.

In the case a plenty of toner remains in the toner cartridge, the supply operation is finished in a short time, and on the other hand, in the case the toner remains little, the supply operation is executed for a long time so as to effectively discharge the toner. The remaining toner amount is predicted by integrating the total operating time of the toner supply motor 1, or counting a time necessary for detecting the presence of the toner again after the start of supplying the toner by a remaining toner amount sensor 24, as a means for grasping the remaining toner amount.