To stably form an image even immediately after switching from a normal mode to a slow mode.

An image forming apparatus comprises: an image carrier; a developer carrier; a first chamber supplying a developer to the developer carrier; a second chamber recovering the developer from the developer carrier after development; conveyance means circularly conveying the developer contained in the first chamber and the second chamber; an execution part capable of executing a first mode for forming an image at a first image forming speed and a second mode for forming an image at a second image forming speed lower than the first image forming speed; and a control part gradually changing, in performing switching between the first mode and the second mode, a target driving speed of the conveyance means so that a driving speed of the conveyance means may be gradually changed from a driving speed of the conveyance means employed in a mode executed before the switching to a driving speed of a steady state of a mode executed after the switching.