To eliminate the necessity of trial printing and to collate a document with a prepared plate material by an image.

The plate material 1 having a relief layer 3A on a floor layer 3B at least and having a colored layer 4 on the relief layer 3A is formed. Projecting parts 8 whose top surfaces 8A form an image part are formed on the relief layer 3A and the colored layer 4 of the plate material 1. The projecting part top surfaces 8A, the relief layer 3A and the floor layer 3B are color-coded to be visually distinguishable.