Integrated circuit (IC) devices are provided including: a first multi-layer wiring structure including a plurality of first wiring layers in a first region of a substrate at different levels and spaced apart from one another, and a plurality of first contact plugs between the plurality of first wiring layers and connected to the plurality of first wiring layers; a through-silicon via (TSV) landing pad including a first pad layer in a second region of the substrate at a same level as that of at least one first wiring layer from among the plurality of first wiring layers, and a second pad layer at a same level as that of at least one first contact plug from among the plurality of first contact plugs and contacts the first pad layer; a second multi-layer wiring structure on the TSV landing pad; and a TSV structure that passes through the substrate and is connected to the second multi-layer wiring structure through the TSV landing pad.