PURPOSE: To prevent the excessive supply and the rising of flocculation rate of the developer and to accomplish the high density and the high definition of an image by performing the initialization of a detection means in a standby time which is until starting an image forming action after turning on a power source and/or until starting the next image forming action after finishing one image forming action.

CONSTITUTION: The detection means 20 detects the quantity of the developer in a developing device 1 and/or a cleaner 70. Initialization means 11 and 12 initialize the detection means 20 specified image forming times and/or at a specified time or every specified image forming time and/or every specified time at the time of consecutively forming the image. The initialization of the detection means 20 is performed in the standby time which is until starting the image forming action after turning on the power source and/or until starting the next image forming action after finishing one image forming action. Thus, the excessive supply and the rising of flocculation rate of the developer are prevented and the high density and the high definition of the image are accomplished.