The structure of poly(N-isopropylacrylamide)-clay nanocomposite gels (NC gel) is investigated. The sophisticated contrast variation small-angle neutron scattering technique leads to obtain the partial scattering functions of each component quantitatively. The extracted partial scattering functions of clay, polymer, and the polymer-clay cross-term are analyzed in detail, and the selective interaction between clay and polymer is revealed. On the basis of these structural observations, it is confirmed that the clay nanoparticles serve as 2-dimensional cross-linkers.