An image forming apparatus includes image bearing members, a latent image forming portion, developing units each including a developing member, a movable member, a common driving source, a contact-and-separation unit, and a control unit. The image forming apparatus is capable of forming the images in an operation in an image forming mode. After end of the latent image formation on one of the image bearing members on which latent image formation is finally started and before end of transfer of an associated image from the one image bearing member, the control unit outputs a spacing signal for spacing associated developing members from the other image bearing members, during the image formation in the operation in the mode.