An image forming apparatus is disclosed that is able to form a full color image with high precision by correcting the adhesion quantity of an image visualizing agent and a position shift of a visible image while continuing to perform a printing process. The image forming apparatus includes an intermediate transfer unit; plural photoconductors; plural charging units; plural exposure units; plural developing units; plural first transferring units; and plural second transferring units. The intermediate transfer unit has a correction pattern image formed in a region outside of a predetermined maximum document region of the intermediate transfer unit in a direction perpendicular to the moving direction. A detector is provided in the intermediate transfer unit for detecting the correction pattern image. A correction controller is provided for correcting, based on detection results of the detector, setting values of one or more of the charging units, the exposure units, and the developing units when a region corresponding to an interval between the visible images passes a position beneath one of the one or more units.