Image forming apparatus

An image forming apparatus comprising:

• a plurality of cartridges each of which comprises a photoconductor;
• a plurality of exposure units each of which is movable between an exposure position proximate to a corresponding photoconductor and a retreating position away from the corresponding photoconductor, a plurality of light-emitting parts being arranged in each exposure unit and configured to expose the photoconductor to light;
• a support frame configured to support the cartridges and allowed to be pulled out from a casing of the apparatus, the support frame comprising a pair of side plates extending in a direction perpendicular to a main direction in which the light-emitting parts are arranged, each of the side plates having guide slots which are configured to guide movement of a corresponding exposure unit between the exposure position and the retreating position, wherein the exposure units are mounted to the support frame;
• arm parts which are swingably mounted to the support frame and by which the exposure units are supported in such a manner that each exposure unit is movable between the exposure position and the retreating position;
• and
• a plurality of first biasing parts each of which is configured to bias a corresponding exposure unit toward the retreating position thereof,
• wherein each of the guide slots comprises a positioning portion configured to position the corresponding exposure unit in a position in a subordinate direction that is perpendicular to the main direction and to an exposure direction in which a light beam is emitted from the exposure unit to the corresponding photoconductor, a distance from each exposure unit in the retreating position to a surface of the corresponding photoconductor in the exposure direction being greater than a distance from the exposure unit in the exposure position to the surface of the corresponding photoconductor in the exposure direction.