A system dynamics model to forecast future movements of a city was studied. The model consists of three sections of population sector, industry sector, land use sector and some divisions of labor, income employment, housing land which connect each sections. Economic growth rate, public investment program, housing land supply program were incorporated in the model as political variables. The model was applied to Okayama city for thirty years from 1975 to 2005. The results of the simulation are summarized as follows: 1) The drift of peoples into Okayama city will advance in the future. 2) Tertiary industries will be given much weight as compared with secondary industries. 3) Because of the drift of peoples, housing problems will be serious in the future.