PURPOSE: To provide a method for automatically manufacturing a mold for forming a product having an irregular pattern corresponding to an optional image with human subjectivity excluded as much as possible.

CONSTITUTION: Information showing the distribution of light and shade in an image 20 is taken in from the image 20. A smoothing process under the consideration of the drawing of a mold for a product is carried out to information showing the distribution of light and shade which have been taken in. Graving information in the case of graving a mold manufacturing member 18 by a cutting means 16 is generated on information showing the distribution of light and shade which have been smoothed. The graving work to the mold manufacturing member 18 is carried out on the generated graving information.