To provide an image forming apparatus which suppresses excessive replenishment of toner associated with erroneous detection of toner concentration by an inductance detecting sensor, so as to suppress fogging and toner scattering and obtain a high-quality image.

The image forming apparatus includes: an image carrier; a conveying means equipped with a developer carrier that carries developer containing non-magnetic toner and magnetic carrier, and configured to stir and convey the developer; a detection means configured to detect information concerning magnetic permeability of the developer in a developing device; a drive control means configured to control drive of the conveying means so that drive speed of the conveying means in a non-developing operation period out of a developing operation period in which an area corresponding to a recording material passing area in an image carrier surface moving direction on a surface of the image carrier passes through a developing part may be lower than drive speed of the conveying means in the developing operation period; and a replenishment amount control means configured to control an amount of toner to be supplied to the developing device based on the detected result detected by the detection means in the non-developing operation period.