Provided is a semiconductor device to which a pattern structure for performance improvement is applied. The semiconductor device includes first and second active regions spaced apart from each other in a first direction with an isolation layer interposed therebetween, a first normal gate formed on the first active region to extend in a second direction crossing the first direction, a first dummy gate having a portion overlapping with one end of the isolation layer and the other portion overlapping with the first active region and spaced apart from the first normal gate in the first direction, a second dummy gate having a portion overlapping with the other end of the isolation layer and the other portion overlapping with the second active region, a first normal source/drain contact formed on a source/drain region between the first normal gate and the first dummy gate, and a dummy contact formed on the isolation layer so as not to overlap with the first and second dummy gates and having a different size from the first normal source/drain contact.