1. An image forming apparatus comprising a rotatable rotating body to and from which a plurality of developer containers can be attached and detached, each of said developer containers being capable of containing developer of a different color, wherein, when said image forming apparatus continuously forms images on a plurality of number of sheets of media using the developer of a single color contained in one of said developer containers attached to said rotating body, said image forming apparatus causes rotational movement of said rotating body at least once at least either when said image forming apparatus starts to continuously form the images, or when said image forming apparatus ends the continuous formation of the images.