An integrated circuit device includes a fin-type active area that extends on a substrate in a first direction, a gate structure that extends on the substrate in a second direction and crosses the fin-type active area, source/drain areas arranged on first and second sides of the gate structure, and a contact structure electrically connected to the source/drain areas. The source/drain areas comprise a plurality of merged source/drain structures. Each source/drain area comprises a plurality of first points respectively located on an upper surface of the source/drain area at a center of each source/drain structure, and each source/drain area comprises at least one second point respectively located on the upper surface of the source/drain area where side surfaces of adjacent source/drain structures merge with one another. A bottom surface of the contact structure is non-uniform and corresponds to the first and second points.