A semiconductor device includes a substrate including a first region and a second region, a first fin-type pattern in the first region, a second fin-type pattern in the second region, a first gate structure intersecting the first fin-type pattern, the first gate structure including a first gate spacer, a second gate structure intersecting the second fin-type pattern, the second gate structure including a second gate spacer, a first epitaxial pattern formed on opposite sides of the first gate structure, on the first fin-type pattern, the first epitaxial pattern having a first impurity, a second epitaxial pattern formed on opposite sides of the second gate structure, on the second fin-type pattern, the second epitaxial pattern having a second impurity, a first silicon nitride film extending along a sidewall of the first gate spacer, and a first silicon oxide film extending along a sidewall of the first gate spacer.