CIRCUIT EXTRACTING METHOD

PURPOSE:To attain the circuit simulation with high accuracy by segmenting the data on the circuit part only out of the entire circuit data with a designated method after extracting the circuit data out of a mask pattern of an LSI. CONSTITUTION:An extracting part 5a is provided to extract a circuit out of a layout pattern together with a segmenting part 5b which segments a partial circuit out of the extracted circuit, and a circuit simulation part 6 which obtains the characteristic of the segmented partial circuit. Then only the circuit part necessary for check of the circuit characteristic is taken out of the circuit extracted from the layout pattern. Thus the data serving as the input of a circuit simulator is produced. As a result, it is not required to previously secure the correspondence between the circuit and the pattern. Then the circuit simulation is attained in consideration of the entire parasitic capacity secured between the segmented circuit part and the removed part. Thus the circuit simulating accuracy is improved.