A risk information processing method used in a risk information processing system that manages a degree of risk at a spot where a moving object is located includes: storing, as risk information in a storage, a degree of risk for a combination of spot and situation; and estimating first risk information for a first combination for which a degree of risk has not been input by using three or more pieces of risk information including degrees of risk for a second combination whose spot is the same as the first combination and whose situation is different from the first combination, for a third combination whose situation is the same as the first combination and whose spot is different from the first combination, and for a fourth combination whose situation is the same as the second combination and whose spot is the same as the third combination.