A semiconductor device includes a first active pattern protruding from a substrate, a second active pattern on the first active pattern, a gate electrode enclosing a sidewall of the second active pattern, a conductive layer pattern on the first active pattern, a first impurity region in the first active pattern, and a second impurity region at a surface portion of the second active pattern. The first active pattern extending along a predetermined direction may have a first region and a second region. The second active pattern may have a pillar structure and the conductive layer pattern may include a metal or a metal compound.