Sheet conveyance unit

A sheet conveyance unit (105) includes first and second conveyance rollers (151A,151B) facing each other, a first stopper (155A) provided at an axial end portion of the first conveyance roller (151A), projecting radially beyond a circumferential surface of the first conveyance roller (151A), downstream rollers (152) positioned downstream from the first and second conveyance rollers (151A,151B) in a sheet conveyance direction, a unit for engaging and disengaging to disengage the first and second conveyance rollers (151A,151B) from each other, and a controller. The first stopper (155A) rotates to a contact position projecting into the sheet conveyance path and to a non-contact position away from the sheet conveyance path as the first conveyance roller (151A) rotates. The first stopper (155A) moves to the non-contact position after stopping a sheet. The first and second conveyance rollers (151A,151B) are disengaged from each other after a leading end of the sheet reaches the downstream rollers (152), before the first stopper (155A) moves to the contact position.