The die casting is widely applied to various industries such as automobile parts, vehicles, electric appliances, construction equipment, measuring instruments, optical equipment and so on because it can be mass-produced and has excellent mechanical properties. But even if there is no abnormality in the external shape, there may be internal voids, cracks, foreign matter, etc. Therefore, non-destructive inspection through X-ray inspection is necessary to lower the defect rate of the product and improve the productivity.