An image processing apparatus comprises an image decoloring unit, an image forming unit, a heater and a control unit. The image decoloring unit decolors an image formed on a sheet with a decolorable color material by heating the sheet. The image forming unit forms an image on a sheet with a decolorable color material. The heater thermally fixes the image formed by the image forming unit on the sheet. The control unit carries out a control processing so that the formation of an image with a decolorable color material is different before and after a specified time elapses from the moment the image decoloring unit completes a decoloring processing.