This study was carried out on DLC thin film deposition technology used in infrared optical system production asa method of reducing the shape changes of the molding core and the consequent loss of life. Experiments on thedeposition on silicon wafer and tungsten carbide used as a substrate for molding core were conducted at eachprocessing condition using a filtered arc system, and it was found that the surface and mechanical properties were ofthe greatest quality when the substrate bias voltage of -150 V was used. In addition, it was confirmed that the PV andRa characteristics were improved by the deposition of the DLC thin film.