A decoloring apparatus includes a sheet conveying unit, a scanner, a decoloring unit, and a controller. The decoloring unit decolors the image on the sheet conveyed through the sheet conveying unit. The decoloring unit is positioned downstream of the scanner in a sheet conveying direction. A distance along the sheet conveying direction between the scanner and the decoloring unit is shorter than a length of a first predetermined sheet size and longer than a length of a second predetermined sheet size. A controller determines whether the sheet conveyed by the sheet conveying unit is the first predetermined sheet size or the second predetermined sheet size. The controller performs a mode limiting process if the sheet size is determined to be the first predetermined sheet size.