To establish a technique for producing a decorative leather product having a high modeling degree by making a pattern on a leather by transfer printing, silk screen printing, ink-jet printing, etc., based on digital image data, integrating the patterning with a three dimensionalization.

In a process before or after a process in which CAD data are prepared according to digital image data of photography, illustration, picture pattern, letter, etc., treated by a computer, a three-dimensional mold for three- dimensional (embossing) processing is produced based on the CAD data, a leather softened by humidification is subjected to three-dimensional formation, the leather is subjected to a pattern treatment for printing an image by a means such as transfer printing, silk screen printing, ink-jet printing, etc., based on the same digital image data and patterning is integrated with a three dimensionalization by three-dimensional formation corresponding to the patterning to give the objective method for plastic processing of natural leather print.