A semiconductor device includes a substrate including NMOS and PMOS regions; first and second active patterns on the NMOS region; third and fourth active patterns on the PMOS region, the third active pattern being spaced apart from the first active pattern; a first dummy gate structure on the first and third active patterns; a second dummy gate structure on the second and fourth active patterns; a normal gate structure on the third active pattern; a first source/drain pattern on the third active pattern and between the normal gate structure and the first dummy gate structure; and a first element separation structure between the first and second dummy gate structures and separating the third and fourth active patterns, wherein the first dummy gate structure includes a first dummy insulation gate intersecting the third active pattern.