To provide an image forming apparatus capable of reducing the increase in angular velocity fluctuation, which occurs in drive transmission of a coupling caused by axial misalignment by accurately aligning the axes of a photoreceptor drive shaft and a photoreceptor shaft in a photoreceptor drum being an image carrier and a rotating body.

In the rotary driving device 25, the photoreceptor shafts 28a and 28b of a photoreceptor 10 are freely rotatably supported by ball bearings 31 and 32 respectively. The photoreceptor drive shaft 29 opposite to the photoreceptor shaft 28b is freely rotatably supported by the slide bearing 33 via a coupling 35. The photoreceptor drive shaft 29 is also freely rotatably supported by a ball bearing 34. The ball bearings 31 and 32, slide bearing 33 and ball bearing 34 are positioned and fixed to the main body 26 of the apparatus. In addition, the axes of the photoreceptor shafts 28a and 28b and the axis of the photoreceptor drive shaft 29 are aligned through axal alignment by positioning means (positioning hole 36 and positioning pin 37), which are independent of the coupling 35.