A semiconductor device including a substrate; gate structures spaced apart from each other on the substrate, each gate structure including a gate electrode and a gate capping pattern; source/drain patterns on opposite sides of the gate structures; first isolation patterns that respectively penetrate adjacent gate structures; and a second isolation pattern that extends between adjacent source/drain patterns, and penetrates at least one gate structure, wherein each first isolation pattern separates the gate structures such that the gate structures are spaced apart from each other, the first isolation patterns are aligned with each other, and top surfaces of the first and second isolation patterns are each located at a level the same as or higher than a level of a top surface of the gate capping pattern.