A semiconductor device includes fin patterns on a substrate, at least one gate electrode intersecting the fin patterns, source/drain regions on upper surfaces of the fin patterns, and at least one blocking layer on a sidewall of a first fin pattern of the fin patterns, the at least one blocking layer extending above an upper surface of the first fin pattern of the fin patterns, wherein a first source/drain region of the source/drain regions that is on the upper surface of the first fin pattern has an asymmetric shape and is in direct contact with the at least one blocking layer.