The first aspect of the present invention is a paper sheet transport mechanism. This mechanism comprises a first paper sheet guide that forms a first paper sheet transport path, the first paper sheet guide having a rotating shaft; a pushing unit that pushes the first paper sheet guide in a specified direction around the rotating shaft; a projecting member that moves in conjunction with movement of the first paper sheet guide; a second paper sheet guide that forms a second paper sheet transport path such that paper sheets are transferred between the first and second paper sheet guides; and a alignment unit that moves in conjunction with a retune movement of the second paper sheet guide to be in contact with the projecting member against the pushing by the pushing unit and to align one end of the first paper sheet guide and one end of the second paper sheet guide.