In sequence data composed of a plurality of event sets with their execution sequence predefined, each of the event sets includes event data indicative of an event to be executed and trigger data defining timing for executing the event. Once a user manually instructs progression instructing operation while the individual events are being executed in accordance with the timing defined by the corresponding trigger data, the next event is executed immediately even before arrival of the next event execution timing. According to another aspect, the trigger data include trigger data of a first type that defines the event execution timing the event by use of an absolute time and trigger data of a second type that defines the event execution timing by use of a relative time between the events, and the sequence data may mixedly include the trigger data of the first and second types. Any one of the two time information can be used appropriately in accordance with characteristics of the individual events. For example, for one event having close relevancy to another event to be executed earlier than the one event, the relative time information is used.