An image forming apparatus includes a photosensitive member, a transfer unit having a transfer belt, a primary transfer roller, a secondary transfer inner roller below the primary transfer roller in a vertical direction, and a stretching roller, a secondary transfer outer roller, a support unit, and an air duct provided in the transfer unit. The secondary transfer outer roller faces the secondary transfer inner roller via the transfer belt and forms a nip portion for secondarily transferring a toner image on the transfer belt to a sheet. The air duct is located downstream of the nip portion in a sheet conveyance direction and below a portion of the transfer belt stretched between the secondary transfer inner roller and the stretching roller in the vertical direction. The air duct includes an air intake port and moves with the transfer unit with movement of the transfer unit from the support unit.