PURPOSE: To enable carving to be easily effectively carried out especially when a drawing pattern of a leather product is treated by a method wherein a pyramid shaped chisel consisting of four sides and four ridgelines is formed of a hard material and besides, respective aperture angles of a side end, a lower end, and the side end to the lower end at a tip part are respectively specified.

CONSTITUTION: A chisel is formed of a hard material of steel, cemented carbide, or ceramics, etc. Then, dimensions and angles of a four side pyramid shape at a tip part 14 of the chisel are constructed as follows. Tlhat is, in a plan at a bladed part of the chisel, a side edge blade aperture angle 7 as given in A-A' sectional part 41 is set to 90±20°. Further, a lower end blade aperture angle 8 as given in B-B' sectional part 42 is also set to 90±20°. Furthermore, a side edge blade to lower end blade aperture angle 9 is also set to 90±20°. Thereby especially when a drawing pattern of a leather product is treated, thrust of a wire drawing start point is improved, and conversion of a wire drawing direction is made free. Besides, a carved seal which is deep in carving will be enabled to be easily effectively carried out.