An image forming apparatus includes an apparatus body, a conveyance unit withdrawably mounted on the apparatus body, and a driving mechanism disposed in the apparatus body. The conveyance unit has a power transmission member which transmits the driving force generated by the driving mechanism to the conveyance member. The power transmission member has a drive input section disposed on the outside of a housing for receiving the driving force. The driving mechanism is disposed on the apparatus body side, and has a drive output section engageable with the drive input section. The drive input section and the drive output section engage with each other in a mounted state that the conveyance unit is mounted on the apparatus body, and the engagement between the drive input section and the drive output section is released in a withdrawn state that the conveyance unit is withdrawn from the apparatus body.