Evaluating the magnitude of vertical and horizontal deformations of foundation plays an important part in many geoteckmical engineering projects. Deformation analysis becomes increasingly important when embankments are constructed on soft grounds. The incorporation of a non-coaxial term into a constitutive equation has no effect on the instantaneous shear modulus for the normal stress difference, but makes the mstantaneous shear modulus for the shear stress smaller. This paper examines the influence of incorporation of a non-coaxial term on the results of deformation analysis. As a result, strain localization was clearly formed in the ground using the non-coaxial model at an embankment height lower than that using the coaxial model.