A semiconductor device includes a semiconductor substrate including an NMOS region and a PMOS region, a gate insulating layer formed on the semiconductor substrate, an NMOS gate formed on the gate insulating layer of the NMOS region, and a PMOS gate formed on the gate insulating layer of the PMOS region. Any one of the NMOS gate and the PMOS gate includes a one-layered conductive layer pattern, and another of the NMOS gate and the PMOS gate includes a three-layered conductive layer pattern.