Image forming apparatus

An image forming apparatus, comprising:

• an image carrier;
• an exposure unit configured to form an electrostatic image by performing scanning exposure of a laser beam to the image carrier;
• a developing unit configured to develop the electrostatic image and to form a toner image on the image carrier;
• a plurality of support rotating bodies;
• a belt member being in contact with the image carrier by being stretched by the plurality of support rotating bodies such that the toner image can be transferred to the belt member from the image carrier;
• a first detection portion detecting a position of the toner image transferred to one end portion of the belt member in a direction orthogonal to a moving direction of the belt member;
• a second detection portion detecting a position of the toner image transferred to another end portion of the belt member in the direction orthogonal to the moving direction of the belt member;
• a third detection portion detecting a position of the toner image transferred to a center portion of the belt member in the direction orthogonal to the moving direction of the belt member;
• and
• a control portion configured to prepare exposure control information correcting an exposure position in a main scanning direction which is a scanning direction of the laser beam per phase position in a sub-scanning direction which is a rotation direction of the image carrier, the control portion having a measuring mode of forming misregistration inspecting toner images at both end portions and a center portion of the image carrier by controlling the exposure unit and the developing unit, of transferring the misregistration inspecting toner images to the belt member, and of detecting the misregistration inspecting toner images by the first, second and third detection portions to obtain position information in the main scanning direction per each phase position in the sub-scanning direction, and preparing the exposure control information from detection results of the first and second detection portions in which an axial moving amount within a rotation cycle of the image carrier is removed on a basis of a detection result of the third detection portion in the measuring mode.