A numerical model was developed to simulate variations of Glaciar Perito Moreno in the Southern Patagonia Icefield. The glacier is a rare target of freshwater calving glacier, on which relatively many scientific observations have been performed. Sensitivities to the glacier flow and variations by hypothetical distributions of englacial water level were investigated through the numerical simulations, and compared with the observation results. Fast glacier flow in the upstream part was simulated fairly well, and inclination of englacial water level was suggested to be steeper at the upstream part than terminal part. Fast flow and surface lowering in the terminal part, however, could not be satisfactorily simulated. The term of longitudinal stress gradient in stress equilibrium, which is ignored in the present simulations, should be important near such calving glacier terminus.