A medium transport device includes a positional corrector configured to transport a medium and correct a position of the medium in a width direction of the medium by moving the medium in the width direction, a first inclination corrector disposed on a transport path of the medium and configured to correct an inclination of the medium relative to a transport direction of the medium, and a second inclination corrector configured to correct the inclination of the medium on an upstream side of the first inclination corrector in the transport direction.

A transport unit transports a transport medium after the transport medium is newly placed as an uppermost medium in a state in which one or a plurality of placed media are already placed in a processing tray. At this state, at least one of the placed media placed on the processing tray is pressed by a pressing unit at a pressing position. After the transport unit is separated away from the transport medium, the pressing unit can move from the pressing position to a retraction position.

A sheet processing apparatus includes a shift unit including a pair of first conveying rollers that nip and convey a sheet and being able to move in a width direction orthogonal to a conveyance direction of the sheet in a state of nipping the sheet; a drive gear configured to transmit a driving force from a drive motor; a rack gear including a rack portion that meshes with the drive gear, the rack gear being configured to receive the driving force from the drive gear via the rack portion and, thereby, move the shift unit in the width direction in a state of nipping the sheet with a pair of first conveying rollers; a guide member configured to guide movement of the shift unit in the width direction; and a supporting member configured to nip the rack gear between the supporting member and the drive gear and support the rack gear, in which the rack gear is rotatable with respect to the shift unit on a plane parallel to the conveyance direction and the width direction.