PURPOSE: To attain revision with high quality without need of sophisticated expert knowledge when a different symbol library is revised, to simplify the job and to reduce the man-hours.

CONSTITUTION: This device is provided with a symbol comparison information table 19 representing cross reference of respective symbols before and after revision, a symbol information matching check means 23 referring to the symbol comparison information table 19 to compare attribute information of each corresponding symbol before and after revision and deciding whether or not matching performance is in existence between the symbols before and after the revision, and a symbol information update means 27 revising the connection information of a new symbol to be in matching with the connection information on a CAD diagram when the presence of matching is decided and informs the operator of that fact on a CRT 35 with respect to a symbol without matching performance when the absence of matching is decided.