An integrated circuit device includes a substrate, first and second fin active regions formed on the substrate and extending in a first direction parallel to a top surface of the substrate, a first gate structure disposed on a side surface of the first fin active region, a pair of first impurity regions respectively formed on a top portion and a bottom portion of the first fin active region, a second gate structure disposed on a side surface of the second fin active region, and a pair of second impurity regions respectively formed on a top portion or a bottom portion of the second fin active region, wherein the pair of first impurity regions vertically overlap each other, and the pair of second impurity regions do not vertically overlap each other.