Provided is a fishing-ground prediction device that predicts fishing grounds by using observational data, which are marine environmental data observed by users, such as the volumes of fish catches, water temperatures, and so forth, and shared observational data that are shared on the basis of sharing information set for the individual users. A fishing-ground prediction system 10 is provided with: an observational-data DB 111 that stores the observational data observed by users, such as the volumes of fish catches, water temperature, and so forth； and a sharing-information DB 130 that stores the sharing information set for the individual users, and shares the observational data on the basis of the sharing information. In addition, a fishing-ground prediction unit 141 that predicts fishing grounds by using the shared data is provided. Because of this, it is possible to efficiently share the observational data, and it is also possible to actively share the data because there is an incentive to do so, that is, providing the observational data allows a user to obtain the observational data collected by others. In addition, because fishing grounds are predicted by using the observational data in which the most recent observational data are recorded, the precision of fishing-ground prediction is enhanced.
