PURPOSE: To easily form a color stereoscopic image by forming an image on a heat expansionary sheet with mixed toner obtained by mixing color toner with toner whose light absorption is excellent, and executing photoirradiation on the heat expansionary sheet.

CONSTITUTION: The mixed toner is obtained by mixing the color toner of a desirable color with the toner whose light absorption is excellent (for example, black toner) is a specified ratio. And the image 4 is formed with the mixed toner by copying on the covered layer 2 of the heat expansionary sheet P. Next, the photoirradiation is executed on the heat expansionary sheet P. The black toner of the image 4 absorbes the energy of light and generates heat, so that fine globes 3 in the covered layer 2 are expanded to protrude the covered layer 2 and the stereoscopic image can be formed. Then, the color stereoscopic image can be easily formed since the image is formed by mixing the color toner with the toner whose light absorption characteristic is excellent.