A thin film transistor substrate of a poly-silicon liquid crystal display device and a simplified method of fabricating the same are disclosed. A liquid crystal display device according to the present invention includes a gate line and a data line connected to a thin film transistor; a gate pad connected to the gate line and a data pad connected to the data line, the data pad having the same cross-sectional structure as the gate pad; and a data link extended from the data pad and connected to the data line via a first contact hole, wherein the data line and the first contact hole are formed inside an area sealed by a sealant.