A method of fabricating a semiconductor device includes forming an interlayer insulating layer on a semiconductor substrate, forming a hard mask layer on the interlayer insulating layer, forming a hard mask pattern in which a plurality of contact hole patterns are formed by patterning the hard mask layer at least two times, conformally forming a supporting liner layer on the hard mask pattern, which supports the hard mask pattern during etching by reinforcing the thickness of the hard mask pattern, forming a plurality of contact hole patterns in the interlayer insulating layer using the hard mask pattern on which the supporting liner layer is formed as an etching mask, and forming contact plugs filling the plurality of contact hole patterns.