PURPOSE: To easily describe the processing algorithm of simultaneously generated events and to enable efficient processing by simulating the event scheduled to be generated in one frame and next simulating performing the simulation limited to the event having intensive chaining with this event.

CONSTITUTION: While successively referring to the scheduled generation time of events, the object to generate the event at the time specified by a route frame is searched, and the simulation of this object is executed. Next, while referring to simultaneously generated event rules, the searched object and the event to be simultaneously generated are listed up, and the object to generate such an event is executed. When these processes are finished, the time of the route frame is updated, and processing is further repeated until the end of simulation time. Thus, the processing algorithm of simultaneously generated events is easily described and further, efficient processing is, enabled so that high-speed simulation can be performed.