Nonlinear ground response anaysis based on a lumped mass system representation was applied to the actual site (Daikoku at Yokohama Port) where earthquake observation has been carried out. Dynamic properties of the soil at the site are expressed by 1)Linear, 2)Bi-linear, 3)Tri-linear, 4)Hardin-Drnevich and 5)Ramberg-Osgood models based on relation between the shear modulus and strain obtained from laboratory soil tests. Using strong motion accelograms, as input motions, whose maximum acceleration had been modified 50, 100Gal, we compared calculation results of these models with computed results by SHAKE, that is a computer program for earthquake response analysis using equivalent linear method. Finally, computaion resulets were compared with records from the observation at the site. 　The results are summerized as follows: 1)The skeleton curves of these models except for the linear model have enough sccuracy to calculate ground response. 2)In the large strain range, the damping ratios calculated from the models did not agree so well with that obtained from the laboratory soil tests. 3)Computed results using the nonlinear models are not much different from that of SHAKE. 4)The models used in the present study explain observed results.