A sheet transport apparatus that re-transports a sheet having an image formed by an image forming portion on a first surface of the sheet, to the image forming portion in order to form an image on a second surface of the sheet on a side opposite to the first surface, the sheet transport apparatus including: a re-transport path through which the sheet is re-transported to the image forming portion again; a cooling unit for blowing air into the re-transport path in order to cool the sheet passing through the re-transport path; and an electrical substrate, in which the air having been blown to the sheet from the cooling unit to cool the sheet is prevented from striking the electrical substrate.