a storage device storing a plurality of stored data and correction information for semiconductor integrated circuits processed in the past, the stored data including layout data converted into a mask data, the correction information including a predictive accuracy of patterns on a wafer and an actual accuracy of patterns on a wafer after optical proximity effect correction related to the stored data;

a plurality of operation processing modules each executing logical operation and arithmetic operation;

a module selecting section selecting at least one of the plurality of operation processing modules as a selected module;

an optical proximity effect correction section, using the selected module, executing optical proximity effect correction on a processing object data for the layout data of a semiconductor integrated circuit by reusing correction information applied for optical proximity effect correction to one of the stored data selected from the plurality of stored data, and generating a corrected processing object data, the selected stored data having coverage equal to that of the processing object data;

a converting section converting the corrected processing object data into mask data by using the selected module; and

a drawing system reading the mask data and drawing a mask pattern corresponding to the semiconductor integrated circuit on a mask substrate.