An integrated circuit device includes a first fin-type active area and a second fin-type active area protruding from a substrate and extending in a first direction, an element isolation layer between the first and second fin-type active areas on the substrate, first semiconductor patterns being on a top surface of the first fin-type active area and having channel areas, second semiconductor patterns being on a top surface of the second fin-type active area and having channel areas, a first gate structure extending on the first fin-type active area in a second direction and including a first work function control layer surrounding the first semiconductor patterns and comprising a step portion on the element isolation layer, and a second gate structure extending on the second fin-type active area in the second direction and including a second work function control layer surrounding the second semiconductor patterns.