Provided are a semiconductor device and a method of fabricating the same. The device may include a transistor on a substrate comprising a gate insulating pattern, a gate electrode and an impurity region, a shared contact plug electrically connected to the gate electrode and the impurity region, and an etch-stop layer between side surfaces of the gate electrode and the shared contact. The shared contact plug may include a first conductive pattern electrically connected to the first impurity region and a second conductive pattern electrically connected to the gate electrode, and a top surface of the first conductive pattern may be higher than a top surface of the gate electrode.