This invention relates to a transflective thin film transistor substrate and a fabricating method thereof that is adaptive for simplifying process, and a liquid crystal display device using the same and a fabricating method thereof.A liquid crystal display device according to an embodiment of the present invention includes a gate line and a data line crossing each other with a gate insulating film to define a pixel area on a first substrate; a thin film transistor connected to the gate line and the data line; a pixel electrode in the pixel area connected to the thin film transistor and to be exposed through a transmission area; a reflection electrode formed in a reflection area having separated areas with the transmission area in between; and an organic insulating film formed under the reflection electrode and formed in a first horizontal area including the reflection area.