A drawing data inputting/interpreting section of a data processing device reads in hierarchical structured drawing data from a first memory device and stores interpreted drawing data information extracted as graphic information in a second memory device. A data analysis section reads in the interpreted drawing data information, analyzes information necessary for a drawing step, and stores the same as drawing analysis results in the second memory device. In addition, a data conversion section reads in the interpreted drawing data information, and after a format conversion to inspection data, stores the converted inspection data in the second memory device. Thereby, a drawing data analysis step and an inspecting data conversion step can be carried out in parallel.