A semiconductor device includes an active fin structure extending in a first direction, the active fin structure including protruding portions divided by a recess, a plurality of gate structures extending in a second direction crossing the first direction and covering the protruding portions of the active fin structure, a first epitaxial pattern in a lower portion of the recess between the gate structures, a second epitaxial pattern on a portion of the first epitaxial pattern, the second epitaxial pattern contacting a sidewall of the recess, and a third epitaxial pattern on the first and second epitaxial patterns, the third epitaxial pattern filling the recess. The first epitaxial pattern includes a first impurity region having a first doping concentration, the second epitaxial pattern includes a second impurity region having a second doping concentration lower than the a first doping concentration, and the third epitaxial pattern includes a third impurity region having a third doping concentration higher than the second doping concentration. The semiconductor device may have good electrical characteristics.