Abstract: The future demand can be forecasted with high accuracy even without the pre-registration of an event schedule. Thus, a demand forecast system performs, for each of a plurality of targets, processes of creating a reference value based on actual demand data indicating a past time-series actual demand value, searching for one or more actual demand values in which a difference between the actual demand value and the reference value exceeds a threshold, and creating event data in which one or more periods according to the one or more actual demand values that were found are used as the one or more time periods of event occurrence.