Semiconductor devices and methods of fabricating the same

A semiconductor device includes a gate electrode extending in a first direction, on a substrate, first outer spacers extending along side surfaces of the gate electrode, a first active pattern extending in a second direction, which intersects the first direction, to penetrate the gate electrode and the first outer spacers, epitaxial patterns on the first active pattern and on side surfaces of the first outer spacers, second outer spacers between the first outer spacers and the epitaxial patterns and inner spacers between the substrate and the first active pattern and between the gate electrode and the epitaxial patterns, wherein in a cross section that intersects the second direction, at least parts of the second outer spacers are on side surfaces of the first active pattern and side surfaces of the inner spacers.