A semiconductor device includes a substrate including a first active region, a second active region and a field region between the first and second active regions, and a gate structure formed on the substrate to cross the first active region, the second active region and the field region. The gate structure includes a p type metal gate electrode and an n-type metal gate electrode directly contacting each other, the p-type metal gate electrode extends from the first active region less than half way toward the second active region.