A method of manufacturing a semiconductor device, including the second sacrificial layer receiving a gate structure include a metal and a spacer on a sidewall of the gate structure therethrough being formed on a substrate. The second sacrificial layer is removed. A second etch stop layer and an insulating interlayer are sequentially formed on the gate structure, the spacer and the substrate. An opening passing through the insulating interlayer is formed to expose a portion of the gate structure, a portion of the spacer and a portion of the second etch stop layer on a portion of the substrate. The second etch stop layer being exposed through the opening is removed. The contact being electrically connected to the gate structure and the substrate and filling the opening is formed. The semiconductor device having the metal gate electrode and the shared contact has a desired leakage current characteristic and resistivity characteristics.