To provide a pattern generating method for a semiconductor device capable of forming a highly reliable semiconductor device, the accuracy of which is high.A method of generating a pattern for a semiconductor device comprises: a step of designing and arranging a layout pattern of a semiconductor chip; a step of extracting an area ratio of the mask pattern from the layout pattern; and a step of adding and arranging a dummy pattern to the layout pattern, while consideration is given to the most appropriate area ratio of the layout pattern of the layer obtained according to a process condition of the layer composing the layout pattern, so that the area ratio of the layer can be the most appropriate area ratio.