A thin film transistor substrate structure for using a horizontal electric field includes a substrate; a gate line and a first common line formed on the substrate parallel to each other from a first conductive layer; a gate insulating film formed on the substrate, the gate line, and the first common line; a data line formed from a second conductive layer on the gate insulating film crossing the gate line and the common line with the gate insulating film therebetween to define a pixel area; a thin film transistor connected to the gate line and the data line; a protective film covering the data line and the thin film transistor; a common electrode formed from a third conductive layer connected to the common line through a hole passing through the protective film and the gate insulating film; and a pixel electrode formed from the second conductive layer connected to the thin film transistor to define a horizontal electric field between the pixel electrode and the common electrode.