An apparatus and method to update patch image formation frequency, in which an electrostatic latent image is formed on an image supporting object, and the electrostatic latent image is developed with a toner. The image formation apparatus includes a developing unit, a toner supply unit for supplying the toner to the developing unit, a patch image density detecting unit for detecting the density of a patch image formed on the image supporting object, a toner density detecting unit for detecting the density of the toner held in the developing unit, and a control unit that adjusts a generating interval of the patch image according to a detection result of the patch image density detecting unit.