A semiconductor circuit pattern design method includes the following operations. A design pattern is created by placing a plurality of cells in each functional block as a unit of the semiconductor circuit and executing routing among the plurality of placed cells. Mask pattern data based on the design pattern is created. A predictive pattern to be formed on the substrate by the mask pattern data is predicted. A difference amount between the predictive pattern and a target pattern to be formed on the substrate by the mask pattern data is checked. The difference amount is compared with a predetermined allowable variation amount. If the difference amount is larger than the allowable variation amount in the comparison, at least one of placement and routing of the cells in the design pattern corresponding to the mask pattern data used to predict the predictive pattern is corrected.