A sheet transport apparatus includes a fixed driving roller and a driven roller capable of coming into contact with or being separated from the driving roller, the driving roller and driven roller being capable of rotating and transporting a sheet interposed therebetween; a rotating-body acceleration sensor moving together with the driven roller and capable of detecting acceleration of movement of the driven roller; and a determining unit for determining, based on the acceleration detected by the rotating-body acceleration sensor, the arrival of a sheet at the driving roller and the driven roller, and the thickness of a sheet.