Image forming apparatus

An image forming apparatus that forms an image on a recording medium, the apparatus comprising:

• an image-bearing-unit support member that is movable between an inside and an outside of the image forming apparatus while supporting a plurality of image bearing units, which each include an image bearing member;
• a belt member that contacts the plurality of image bearing members;
• and
• an image-bearing-unit operating member that moves the image bearing units relative to the image-bearing-unit support member when the image-bearing-unit support member is inside the image forming apparatus, thereby moving the image bearing units from a contact position where the image bearing units contacts the belt member to a separate position where the image bearing units are separated from the belt member
• wherein the image-bearing-unit operating member causes at least one of the plurality of image bearing units to be started to move from the contact position toward the separate position at different timing from timing at which the image-bearing-unit operating member causes the other image bearing unit or the other image bearing units to be started to move from the contact position toward the separate position.