Abstract: A dynamic simulation system in which an internal model is dynamically changed according to input data. The status of variation of the internal model is inputted, and the display and/or sound output of the internal model is dynamically changed according to the status of variation thus inputted. In the dynamic simulation, not only the state of a model is displayed, but also the status of variation of the model is outputted as display data or sound data. Accordingly, the operator can readily recognize the amounts of variation calculated during simulation.