Image forming apparatus

An image forming apparatus comprising:

• an image bearing member rotatable with carrying an electrostatic image;
• an exposing means for forming the electrostatic image by executing a scanning exposure at an exposing position with respect to the image bearing member;
• a developing means for developing the electrostatic image at a developing position, comprising a plurality of developing devices, a rotating member including a first gear portion for receiving a driving force to rotate, rotatable while supporting the plurality of the developing devices, and a driving means including a second gear portion for transmitting the driving force to the first gear portion with being geared with the first gear portion at a drive transmitting position and selectively moving the plurality of the developing devices to the developing position,
• wherein an angle θe(°) formed by a straight line linking a rotation center of the rotating member and the drive transmitting position and a tangent of the image bearing member at the exposing position satisfies the following relationship with the premise that a pressure angle of the gear in the first and second gear portions is α(°) and the image bearing member rotating direction is positive:
• −α≦θe≦α, in which 14°≦α≦20°.