A decoloring device according to an embodiment comprises a decoloring unit configured to erase a first image formed with erasable colorant on a first side of a sheet and a second image formed with erasable colorant on a second side of the sheet, and a reading unit configured to read the first and second sides of the sheet and determine whether the first side and the second side are reusable. The decoloring device further comprises a single-side reusable paper tray configured to stack the sheet if the reading unit determines that only one of the first and second sides is reusable, and a reversing unit configured to reverse the sheet and discharge the sheet to the single-side reusable paper tray so that the one of the first and second side determined to be reusable is stacked on the single-side reusable paper tray in a predetermined orientation.