Disclosed is a thin film transistor substrate for a fringe filed switching type liquid crystal display device, and a fabrication method thereof, that reduces the number of required mask processes, and thus improves fabrication efficiency. The fabrication method involves three mask processes, wherein the masks are partial transmitting masks, and the resulting photo-resist patterns have varying thicknesses. By having photo-resist layers of varying thicknesses, structures can be formed in multiple etching steps using the same photo-resist pattern by incrementally removing the photo-resist according to its thickness. The thin film transistor substrate has a common line, a common electrode, a gate line and a gate electrode formed directly on the substrate. The common electrode overlaps the pixel electrode in the pixel area.