An image forming apparatus for forming an image on a recording material includes a main assembly to which a cartridge including an image bearing member on which a latent image is formed and including a developing device for developing the latent image on the image bearing member is detachably mountable, and a transfer unit, detachably mountable to the main assembly separately from the cartridge, for transferring a developer image formed on the image bearing member. The developing device includes a developer carrying member and is movable between a contact position where the developer carrying member is contacted to the image bearing member and a spaced position where the developer carrying member is spaced from the image bearing member. The transfer unit includes a developing device contact-and-separation mechanism for moving the developing device between the contact position and the spaced position.