An image forming apparatus which forms an image by using a unit having at least a member associated with image formation and storage unit storing information, comprising, an image carrier, developing unit for developing a latent image formed on said image carrier by supplying toner to said image carrier and controller for controlling image formation operation on the basis of the information stored in said storage unit, wherein said storage unit stores information for controlling toner consumption operation in accordance with a characteristic of the toner, and said controller controls the toner consumption operation on the basis of the information stored in said storage unit without printing any image on a print medium.