An integrated circuit device according to the inventive concepts includes lower wiring structures formed on a substrate, an air gap arranged between the lower wiring structures, a capping layer covering an upper surface of the air gap, an etch stop layer conformally covering an upper surfaces of the lower wiring structures and the capping layer and having a protrusion and recess structure, an insulating layer covering the etch stop layer, and an upper wiring structure penetrating the insulating layer and connected to the upper surface of the lower wiring structure not covered with the etch stop layer, wherein the upper wiring structure covers a portion of an upper surface of the capping layer, and a level of the upper surface of the capping layer is higher than a level of the upper surface of the lower wiring structures.