A semiconductor integrated circuit design method has extracting connection-permitted patterns which are permitted to connect to each other in a layout pattern, disconnection-permitted patterns which exercise no effect on a circuit operation even when disconnected in the layout pattern, and a multicut via which suffices when connection is made to at least one via thereof in the layout pattern, by using a net list and a cell library; conducting LRC (Lithography Rule Check) processing on the layout pattern to which a correction pattern resulting from OPC (Optical Proximity Correction) processing is added, and detecting an error part; and judging the error part either as a false error when the error part is included in the connection-permitted patterns, the disconnection-permitted patterns, or the multicut via extracted, or as a true error when the error part is not included in the connection-permitted patterns, the disconnection-permitted patterns, or the multicut via extracted, and making a pattern correction to the error part when the error part is judged as the true error.