To determine seismic ground motion for seismic design, it is necessary to take site effects into account, such as non-linearity of soil and geological irregularities. In this paper, we discuss these two aspects of site effects. The two-dimensional FEM computer program, therefore, is developed which can take into account the soil non-linearity. From an analytical study, the characteristics of nonlinear wave propagation in soil deposit with a basin edge are clarified.