A control unit sets a first feedback gain for suppressing an angular speed variation of a first frequency, which causes a misalignment of images to be overlaid with each other, to the first feedback unit in a first image forming mode in which images formed on the first and the second image carriers are overlaid, and sets a second feedback gain for suppressing an angular speed variation of a second frequency, which causes a periodic uneven density on an image that is to be formed with a uniform density, to the first feedback unit in a second image forming mode in which an image is formed using the first image carrier.