A liquid crystal display device and a fabricating method thereof for simplifying a process are disclosed. In the method of fabricating the liquid crystal display device, a first conductive pattern group including a gate line and a gate electrode, a common line and a common electrode, a pixel electrode and a pad is formed on a substrate. An insulating film including a plurality of contact holes and a semiconductor pattern is formed on the first mask pattern group. And a second conductive pattern group including a data line, a source electrode and a drain electrode is formed on an insulating film provided with the semiconductor pattern, and exposes an active layer of the semiconductor pattern.