In a semiconductor device, a first active area, a second active area, and a third active area are formed on a substrate. A first gate electrode is formed on the first active area, a second gate electrode is formed on the second active area, and a third gate electrode is formed on the third active area. The first gate electrode has a first P-work-function metal layer, a first capping layer, a first N-work-function metal layer, a first barrier metal layer, and a first conductive layer. The second gate electrode has a second capping layer, a second N-work-function metal layer, a second barrier metal layer, and a second conductive layer. The third gate electrode has a second P-work-function metal layer, a third capping layer, a third N-work-function metal layer, and a third barrier metal layer. The third gate electrode does not have the first and second conductive layers.