Abstract: When a pattern is manually drawn on a tablet with an electronic pen, a computer executes a graphic processing to display on a CRT a geometrically defined pattern which best resembles the manually drawn pattern. Moreover, a pattern element is erased, divided or copied by memorizing a graphic processing command in advance in a manner to correspond to a predetermined pattern or operator and by manually drawing this operator on the tablet with the electronic pen.The pattern data can be inputted to the computer to display the pattern by the same operations as those for drawing on a paper with writing apparatus so that the pattern can be drawn on the basis of the human engineering without feeling any physical disorder.