CAD (Computer Aided Design) data which is reticle design data is input to first and second data conversion devices which respectively convert the CAD data to electron beam (EB) write data and inspection data. The EB write data and inspection data output are input to a data verification device to verify whether or not there is a data conversion error. If no data conversion error is detected by the data verification device, an EB writing device writes a pattern on an unwritten reticle with an electron beam based on the EB write data and develops the reticle, after which the fabricated developed reticle is inspected by a reticle inspection device. As a defect, such as a data conversion error contained in EB write data is detected before fabrication of a reticle, the reticle inspection process is simplified, the effective availability factors of the EB writing device and reticle inspection device and the time needed to fabricate a reticle is made shorter, thereby reducing the fabrication cost.