The microscopic structures of clay polymer aqueous solutions under shear deformation were investigated by means of small-angle neutron scattering (SANS). Lapointe (clay) platelet dispersions in poly(ethylene oxide) (PEG) aqueous solutions with various deuterious/hydrogeneous water compositions were prepared, and contrast-variation SANS experiments were carried out. Reversible shear-thinning behaviors were observed in both clay dispersions and PEG solutions. No anisotropy was observed in SANS patterns even though clay platelets are highly anisotropic, indicating rotation of platelets in a shear flow. In the presence of PEG, on the other hand, a strong anisotropic SANS pattern was observed in the shear flow. This suggests that clay platelets are embedded in a cloud of PEO chains and the cloud is elongated along the shear flow direction by shearing, resulting in a strong clay orientation. Contrast-variation SANS clearly exhibited shear-induced adsorption-desorption of polymer chains on the clay surface.