Abstract: An image decoloring device includes: a decoloring processing unit configured to perform decoloring for removing the color of a decolorable colorant; a sheet carrying unit configured to transfer a sheet and causing the sheet to pass through the decoloring processing unit; a print condition detection unit arranged upstream of a direction in which the sheet is transferred by the sheet carrying unit with respect to the decoloring processing unit, the print condition detection unit obtaining print condition information indicating the print condition of an image formed on the sheet; and a process controlling unit configured to control the decoloring processing unit based on a result of detection given from the print condition detection unit.