PURPOSE: To confirm the shape of a gaphic during preparation in the course of coordinates input at the time of plotting a polygonal line or polygon by means of coordinate input.

CONSTITUTION: The device consists of a control part 1 controlling an entire device, a coordinate input device 2 inputting the coordinates of point for plotting the polygonal line or polygon in a displayed dialog box, a coordinate transforming means 3 transforming the inputted coordinates from a position on an actual sheet size into the position on a display area serving as a working panel corresponding to the sheet size, a display memory 4 storing the position on the display area, a display control part 5 controlling the display of the polygonal line or polygon whose coordinates are inputting, and a CRT 6 making the display.