PURPOSE: To provide a parts drawing generation method in a CAD system where the generation man-hour of a similar parts drawing can be reduced.

CONSTITUTION: A drawing frame which is previously registered is read (S10), and a parts drawing is plotted (S13) and registered (S15). For generating the similar drawing, the drawing frame of the parts drawing on a screen is eliminated (S18), and the new drawing frame is read (S20). It is allocated to the parts drawing from which the drawing frame is eliminated and it is set to be the new parts drawing. Then, it is corrected so as to execute plotting (S23). The drawing which is newly plotted is registered and the plotting of the similar drawing completes. The drawing can be exchanged even in a column frame to which related information on the parts are filled and the colorful similar drawing can speedily be generated by freely using the both frames.