PURPOSE: To realize a more sufficient color-forming of a dye to further enhance the color-forming density and sharpness of an image, by a method wherein the formed image is heated by a thermal head, a heat roll, a heat plate, and other heating means after or during the forming of the image.

CONSTITUTION: A recorder comprises a thermal head 12 as an example of a means heating the back face of a transfer sheet 10 corresponding to an image form at a part where the thermal transfer sheet 10 is overlapped with a transferred material 11 and a pair of heat rolls 14, 14' uniformly heating the transferred material 11 having the image. A heating temperature of the rolls is variably set according to the type of a transferred material and the carry speed thereof, but is preferably the order of 50W200°C. The surface applied with the image is heated by the heating means, whereby the image is heated all over. In this manner, a dye forming the image forms color sufficiently to be satisfactorily fixed into the transferred material; thus, an image having superior color-forming density, light fastness, stain resistance, etc. is made available.