To remove, in an inexpensive simple structure, jammed paper removing on a conveyance roller using a mechanical clutch, in an image forming apparatus including a gear train which transmits drive force to a processing unit comprising at least an image carrier and a developing device sharing the same motor, to a fixing/ejection system and to a sheet feed/conveyance system and which conveys a recording sheet by means of the conveyance roller using the mechanical clutch.

In the image forming apparatus, the gear train which transmits drive force to the processing unit and the fixing/ejection system includes a reverse rotation prevention mechanism which stops transmission of reverse rotation to the processing unit and the fixing/ejection system. The motor can be reversely rotated such that the reverse rotation of the conveyance roller connected to a means which mechanically transmits or stops drive force is not transmitted to the processing unit and the fixing/ejection system. Thus, a jammed recording sheet is removed.