The nanocomposite (NC) gels made of poly(N-isopropylacrylamide) (PNIPA) and synthetic clay show extraordinarily high mechanical properties, e.g., high extensibility and high strength at break. The structure and deformation mechanism of the NC gels have been investigated by small-angle neutron scattering (SANS). Two-dimensional SANS intensity patterns were obtained for deformed NC4 gels with the stretching ratio up to 6 times, where 4 denotes the clay concentration being 0.04 mol/L (approximate to 3.05 wt %). A so-called abnormal-butterfly pattern was observed in the low q region, i.e., q < 0.02 angstrom(-1), while a normal-butterfly pattern was obtained in the larger q (>= 0.02 angstrom(-1)). Here q is the magnitude of the scattering vector. However, contrast-matched SANS experiments disclosed that the abnormal-butterfly pattern is not originated from cross-link inhomogeneities observed in conventional gels but from oriented-clay platelets by deformation. These results indicate that clay platelets, 300 angstrom in diameter and 10 angstrom thick embedded in the PNIPA network, are highly aligned with their surface normal parallel to the stretching direction, and the PNIPA chains are elongated parallel to the stretching direction. It is concluded that the high mechanical properties of NC gels are ascribed to "plane cross-linking" with long PNIPA chains between platelets compared with those of conventional chemical gels having "point cross-linking".