To reduce an abrasion of an engraving bite and to efficiently carry out an engrave having a desired padding-stop shape by preparing a cutter path for an NC machining tool carrying out a shrinkage processing a line drawing data at plural number and engraving on a base material such as a metal using a plurality of an engraving bite having a different tip end shape.

A line drawing manuscript is image-inputted and an outline trace is carried out, if necessary, against a bit map image in which a noise is removed by a picture element unit. Finally, an outline V0 of a line picture image is obtained as a vector data. Until a cutter path in which an outline inside of the line picture image is produced just enough, a shrinkage processing is subsequently repeated and a cutter pathes V1, V2, V3, V4, V5 is obtained. Next, a text processing for imparting a code for mechanical control is made, thereby making a data for NC machining tool of four axle control. An intaglioed picture line forming body having a padding-stop and a different cross shape is made on a base material such as metal based or the data using a plurality of engraving bite having a different tip shapes.