To provide an image forming device which eliminates the need to strictly position rotary shafts of a driving and a driven sides (center adjustment), generates no abnormal sound, and has a compact and inexpensive coupling means having high-durability.

In the image forming device having the coupling means for driving transmission between the rotary shaft of the driving side and the rotary shaft of a device unit as the driven side, an elastic member is used for the rotary shaft of the driving side or the rotary shaft of the device unit.