A method of creating writing data for writing a pattern on a target workpiece by using a writing apparatus provided with a plurality of columns that emit charged particle beams includes inputting information on distance between optical centers of the plurality of columns, inputting layout data and virtually dividing a writing region indicated by the layout data into a plurality of small regions, by a width of one integer-th of the distance indicated by the information on distance, converting, for each small region, the layout data to a format adaptable to the writing apparatus to create, for the each small region, the writing data whose writing region is divided into the small regions, and outputting the writing data.