PURPOSE: To improve programming efficiency by designating coordinates interactively with a display device in the case of preparing a graphic program.

CONSTITUTION: Display devices 5 to 7 displaying characters and graphics and pointing devices 1 to 3 designating a position within the display devices 5 to 7 are provided. So that a graphic is prepared with a CAD(Computer Aided Design), the graphic is prepared by the pointing devices 1 to 3 interactively with the display devices 5 to 7, thereby performing the coding of the graphic program automatically by a central processing unit 8. Thus, by once preparing the graphic on the paper, the time and labor for designating respective coordinates of the graphic are eliminated and the graphic program is also prepared simultaneously with the graphic by using interactively the pointing devices 1 to 3.