This invention provides an image forming apparatus capable of shortening the user's print waiting time as much as possible when it is determined that image adjustment is necessary during the image forming operation, and a control method therefor. To accomplish this, in a color image forming apparatus including a plurality of image forming stations which form toner images with a plurality of toners on the basis of a job, it is discriminated whether adjustment processing is necessary during a continuous image forming operation based on the job. If it is discriminated that adjustment processing is necessary, it is determined whether each of the image forming stations has a non-operating time enough to execute the discriminated adjustment processing during the image forming operation. The image forming station determined to have a non-operating time enough to execute adjustment processing executes the discriminated adjustment processing during the non-operating time.