A paper-sheet processing apparatus comprising: a casing; a take-in unit configured to take in paper sheets into the casing; a recognition unit configured to recognize each of the paper sheets taken in by the take-in unit; an operation display unit on the front side of the casing configured to receive input from the operator and also to display information; a transport unit (30, 40, 50) configured to transport the paper sheets taken in by the take-in unit, the transport unit including a horizontal transport unit configured to transport the paper sheets recognized by the recognition unit, along a horizontal direction; wherein the transport unit (30, 40, 50) includes: - a first transport unit configured to transport, to one side of a horizontal direction, the paper sheets taken in by the take-in unit; - a second transport unit positioned below the first transport unit and configured to transport, to another side of the horizontal direction, the paper sheets transported by the first transport unit, the other side being opposite to the one side of the horizontal direction; and - an intermediate transfer unit configured to connect the first transport unit and the second transport unit, wherein the recognition unit is configured to recognize each of the paper sheets transported by the first transport unit, and the horizontal transport unit is included in the second transport unit; the paper-sheet processing apparatus further comprising a plurality of stacking units (80, 90) each positioned below the horizontal transport unit, and each having an opening on the front side of the casing, and configured to stack the paper sheets transported by the horizontal transport unit and determined by the recognition unit to satisfy a predetermined condition; and a plurality of stacking wheels (81, 91) provided correspondingly to the stacking units (80, 90) and used for stacking the paper sheets transported by the horizontal transport unit in the stacking units, wherein for any adjacent two stacking units among the plurality of stacking units (80, 90), the rotation direction of one of the stacking wheels (81, 91) corresponding to one of the two stacking units and the rotation direction of the other stacking wheel corresponding to the other stacking unit are opposite to each other; wherein one of the adjacent two stacking units is configured to stack the paper sheets while tilted at an angle of at least 45 degrees to a transport direction of the paper sheets by the horizontal transport unit, and the other stacking unit is configured to stack the paper sheets while tilted at an angle of at least 45 degrees to another side of the horizontal direction, the other side being opposite to the transport direction of the paper sheets by the horizontal transport unit; wherein two adjacent stacking units are arranged in parallel in the left and right direction as viewed from the front side of the casing. a casing; a take-in unit configured to take in paper sheets into the casing; a recognition unit configured to recognize each of the paper sheets taken in by the take-in unit; an operation display unit on the front side of the casing configured to receive input from the operator and also to display information; a transport unit (30, 40, 50) configured to transport the paper sheets taken in by the take-in unit, the transport unit including a horizontal transport unit configured to transport the paper sheets recognized by the recognition unit, along a horizontal direction; wherein the transport unit (30, 40, 50) includes: - a first transport unit configured to transport, to one side of a horizontal direction, the paper sheets taken in by the take-in unit; - a second transport unit positioned below the first transport unit and configured to transport, to another side of the horizontal direction, the paper sheets transported by the first transport unit, the other side being opposite to the one side of the horizontal direction; and - an intermediate transfer unit configured to connect the first transport unit and the second transport unit, - a first transport unit configured to transport, to one side of a horizontal direction, the paper sheets taken in by the take-in unit; - a second transport unit positioned below the first transport unit and configured to transport, to another side of the horizontal direction, the paper sheets transported by the first transport unit, the other side being opposite to the one side of the horizontal direction; and - an intermediate transfer unit configured to connect the first transport unit and the second transport unit, the paper-sheet processing apparatus further comprising a plurality of stacking units (80, 90) each positioned below the horizontal transport unit, and each having an opening on the front side of the casing, and configured to stack the paper sheets transported by the horizontal transport unit and determined by the recognition unit to satisfy a predetermined condition; and a plurality of stacking wheels (81, 91) provided correspondingly to the stacking units (80, 90) and used for stacking the paper sheets transported by the horizontal transport unit in the stacking units,