Integrated circuit devices including a fin shaped active region and methods of forming the same are provided. The devices may include a fin shaped active region, a plurality of semiconductor patterns on the fin shaped active region, a gate electrode on the plurality of semiconductor patterns, and source/drain regions on opposing sides of the gate electrode, respectively. The gate electrode may include a main gate portion extending on an uppermost semiconductor pattern and a sub-gate portion extending between two adjacent ones of the plurality of semiconductor patterns. The sub-gate portion may include a sub-gate center portion and sub-gate edge portions. In a horizontal cross-sectional view, a first width of the sub-gate center portion in a first direction may be less than a second width of one of the sub-gate edge portions in the first direction.