To solve problems that, although a relief engraving in which Chinese characters or other characters are engraved in one wooden original plate is highly evaluated as having dignity and elegance, skillful high technique by a craftsman, a huge time and huge labor are required, so that finished work becomes extremely expensive in the formation of relief engraving in which complicated and delicate curves such as Sosho (the cursive style of writing Chinese characters), Kuzushimozi (the fully cursive style of the same) or the like are engraved, and that the production of a plurality of works having the same character styles in large quantities is impossible.

When engraving characters having complicated curves which most require a skillful technique and time, the engraving is performed with a constant depth and accuracy in a short period of time by using a special jigsaw in which a length of a cutting blade is adjusted. The cutting blade used for the jigsaw does not penetrate a wooden original plate but is adjusted so as to cut at an arbitrary depth. The same effect can be obtained for a hard raw wood such as oak, zelkova or the like by being replaced with a cutting blade for the hard raw wood.