A driving device for driving a driven member includes a driving source; a driving gear fixed to a rotation shaft of the driving source; at least one gear for transmitting rotational motion of the driving gear to the driven member; a rotation detection gear engaged with the at least one gear; a detector for detecting rotation of the rotation detection gear; and a controller for detecting an angular speed and a rotational phase of the rotation detection gear on the basis of information from the detector and for controlling the rotational speed of the driving source such that a rotation period of the rotation detection gear is a non-integer multiple of a rotation period of the driving gear.