A method of fabricating a liquid crystal display device includes forming a data bus line on a substrate, forming a preliminary interlayer insulating layer having a first thickness on the substrate including the data bus line, forming an interlayer insulating layer by etching the preliminary interlayer insulating layer to a second thickness less than the first thickness, the interlayer insulating layer having a planarized surface, sequentially forming a semiconductor layer, a gate insulating layer, and a gate electrode on the interlayer insulating layer, forming a passivation layer on the substrate, forming a plurality of contact holes exposing portions of the data bus line and the semiconductor layer by etching portions of the passivation layer, and forming a pixel electrode on the passivation layer.