PURPOSE: To automatically prepare partial drawings, and to improve the effect of saving labor by preparing sectional drawings as one single graphic when the graphics which enter the graphics don't exist, and displaying each of the position size of the graphics and information for working on the drawings.

CONSTITUTION: A computer 1 is equipped with a keyboard 2 for inputting a data, graphic display device 3 which displays both the graphic and a message, disk device 4 which stores both a program and a graphic data, and an arithmetic processor 5 which executes the program and controls equipments totally. Then, the computer 1 judges the presence of the graphics which enter the graphics in the partial drawings at the time of preparing the partial drawings. When the graphics which enter the graphics are present, the computer 1 prepares the sectional drawings after defining these graphics as one graphic, and combining each information for processing into one. When the graphics which enter the graphics are not present thereon, the computer 1 prepares the sectional drawings as the single graphic, and displays each of the position size of the graphics and the information for working corresponding to a graphic character on the drawings. Thus, the partial drawings can be prepared by an automatic process, the number of designers can be reduced, lead time can be shortened, and an error can be prevented.