A method for forming patterns of a semiconductor device includes sequentially forming a hard mask layer, a sacrificial layer, and an anti-reflection layer on a substrate, the substrate including a cell region and a peripheral circuit region, patterning the sacrificial layer to form a first sacrificial pattern on the cell region and a second sacrificial pattern on the peripheral circuit region, forming spacers covering sidewalls of the first and second sacrificial patterns, and removing the first sacrificial pattern. The anti-reflection layer includes a lower anti-reflection layer and an upper anti-reflection layer which are formed of materials different from each other. In the patterning of the sacrificial layer, the anti-reflection layer is patterned to form a first anti-reflection pattern on the first sacrificial pattern and a second anti-reflection pattern on the second sacrificial pattern. The second anti-reflection pattern remains when the first sacrificial pattern is removed.