Methods of forming patterns of a semiconductor device are provided. The methods may include forming a hard mask film on a semiconductor substrate. The methods may include forming first and second sacrificial film patterns that are spaced apart from each other on the hard mask film. The methods may include forming a first spacer on opposing sidewalls of the first sacrificial film pattern and a second spacer on opposing sidewalls of the second sacrificial film pattern. The methods may include removing the first and second sacrificial film patterns. The methods may include trimming the second spacer such that a line width of the second spacer becomes smaller than a line width of the first spacer. The methods may include forming first and second hard mask film patterns by etching the hard mask film using the first spacer and the trimmed second spacer as an etch mask.