An image forming apparatus including a replaceable container having toner stored therein includes: an image forming unit including an accumulating unit for accumulating developer containing toner and configured to form an image by using the developer in the accumulating unit; a measurement unit configured to measure a toner density in the accumulating unit; a portion to which the container is attached; a supplementing unit configured to supplement the toner from the attached container to the accumulating unit; and a controller configured to control the supplementing unit based on first information corresponding to a difference between the toner density and a target toner density and second information corresponding to an accumulated value obtained by accumulating differences, wherein the second information does not change in a period from replacement of the container by another container until a predetermined number of times of supplement is performed.