In a paper-sheet post-processing device, a paper-sheet aligning unit has: a main unit; a paper-sheet holding part which holds paper-sheets supported on a paper-sheet supporting unit; a cam mechanism which places the paper-sheet pressing part close to and separate from the paper-sheet supporting unit; and an aligning mechanism which aligns the paper-sheets supported on the paper-sheet supporting unit with a standard position by rotation of the aligning member; and the main unit has a rotation shaft rotatably supported axially by a first support part and a second support part and the cam member and aligning member are arranged to be fixed to the rotation shaft.