1. An image forming apparatus that determines an image forming condition by using an image-adjusting pattern image, the apparatus comprising: a detection unit detecting information about the image-adjusting pattern image fixed to a paper; a determination unit which, on the basis of an image-noise detecting pattern image that is formed on the paper prior to forming the image-adjusting pattern image, determines the presence or absence of an image noise generated in the image-adjusting pattern image; and a control unit which, on the basis of a determination result of the determination unit, sets a detection region where the detection unit detects information about the image-adjusting pattern image, to a region where the image noise is not generated, and which further determines the image forming condition by using the information detected in the detection region.