In accordance with an embodiment, a management system comprises a first information generation section, a second information generation section, a storage section and a determination section. The first information generation section generates first information indicating that a processing of forming an image on a sheet is executed at the time information instructing formation of the image is input. The second information generation section generates second information indicating that a processing of decolorizing the image formed on the sheet is executed at the time information instructing a processing of decolorizing the image is input. The storage section stores the first information and the second information. The determination section determines whether or not the processing of decolorizing the image formed on the sheet is executed on the sheet by a predetermined time point preset in the management system based on the first information and the second information.