PURPOSE: To increase the density of a first dye image by heating a first dye donator material conforming to an image, transferring the first dye image to a dye image receiving layer of a receiving sheet, then, heating a second dye donator material conforming to the image, and transferring the second dye image to a dye image receiving layer provided on the other side of the receiving sheet, as a mirror image.

CONSTITUTION: A first dye-donator material 5a including a supporting body which has a dye-binder layer on the top, is heated conforming to an image, and a first dye image is transferred to a dye image receiving layer 7a which is provided on one side of a transparent film carrier of a receiving sheet 2. Then, a second dye-donator material 5b including a supporting body which has a dye-binder layer on the top, is heated conforming to the image, and the second dye image having the same hue as the hue of the first dye image, is transferred to a dye receiving layer 7b which is provided on the other side of the transparent film carrier of the receiving sheet 2. The second dye image is a mirror image of the first dye image, and increases the density of the first dye image under a state wherein the second dye image matches the first dye image.