PURPOSE: To prevent an incorrect drawing correction by executing electronically the integrated management of drawing information and revision management information and executing the generation management with regard to new and old mutual generated drawings.

CONSTITUTION: In the CAD system having a system control means 2, a screen operating means 3, a graphic input means 4, a graphic operating means 5, a drawing output means 6 and a file operating means 7, this system is provided with a drawing managing means 8 for managing a drawing name and a drawing number, a drawing comparing means 9 for comparing the information of plural drawing files, an approval managing means 10 for managing an approval procedure, and an on-line managing means for transmitting and receiving the drawing information by a circuit.