Provided is a semiconductor device comprising an active region on a substrate and including first and second sidewalls extending in a first direction and an epitaxial pattern on the active region, wherein the epitaxial pattern includes first and second epitaxial sidewalls extending from the first and second sidewalls, respectively, the first epitaxial sidewall includes a first epitaxial lower sidewall, a first epitaxial upper sidewall, and a first epitaxial connecting sidewall connecting the first epitaxial lower sidewall and the first epitaxial upper sidewall, the second epitaxial sidewall includes a second epitaxial lower sidewall, a second epitaxial upper sidewall, and a second epitaxial connecting sidewall connecting the second epitaxial lower sidewall and the second epitaxial upper sidewall, a distance between the first and second epitaxial upper sidewalls decreases away from the active region, and the first and second epitaxial lower sidewalls extend in parallel to a top surface of the substrate.