A semiconductor device is manufactured using dual metal silicide layers. The semiconductor device includes a substrate having first and second regions, a first metal gate electrode on the substrate in the first region, a second metal gate electrode on the substrate in the second region, a first epitaxial layer on and in the substrate at both sides of the first metal gate electrode, a second epitaxial layer on and in the substrate at both sides of the second metal gate electrode, a first metal silicide layer on the first epitaxial layer, a second metal silicide layer on the second epitaxial layer, an interlayer dielectric layer on the first and second metal silicide layers, contact plugs passing through the interlayer dielectric layer and electrically connected to the first and second metal silicide layers.