As seen at Port Island vertical array record during the 1995 Hyogoken-Nambu earthquake, the soil deposits have the upper limit of ground motions because the soil layer can not transfer the shear force larger than its shear strength to upper layers. In order to clarify the relation between the shear strength of soil and upper limit of ground motion, nonlinear analyses are carried out focused on the angle of internal friction. It is shown that upper limit of PGA, JMA seismic intensity scale and SI value are controlled by the angle of internal friction.