In one embodiment, the semiconductor device includes at least one active fin protruding from a substrate, a first gate electrode crossing the active fin, and a first impurity region formed on the active fin at a first side of the first gate electrode. At least a portion of the first impurity region is formed in a first epitaxial layer portion on the active fin. A second impurity region is formed on the active fin at a second side of the first gate electrode. The second impurity region has at least a portion not formed in an epitaxial layer.