PROBLEM TO BE SOLVED: To provide a fishery forecasting system capable of being originally constructed by a user, based on experience and information which have been acquired by the user until now. SOLUTION: This fishery position forecasting system 12 has a download tool 13 which downloads oceanic condition information from a data base 6 and a fish catch information data base 16 in which past actual results are accumulated. In an optimal fishery condition extracting function 17, relation between ocean information in fish catch and amounts of the fish catch, etc., accumulated in the data base 16 is spatially and temporally analyzed by being synchronized with numerical data accumulated in the data base 6 or numerically expressed information on ocean environment and fishing, so that a condition under which a probability for forming a most favorable fishery point in an arbitrary ocean area and season is high is extracted and parameterized. A favorable fishery position calculating function 19 calculates a favorable fishery position by using an optimal parameter. The calculated favorable fishery position is displayed on a display device 22 by a fishery and oceanic condition information displaying function 21. COPYRIGHT: (C)2006,JPO&NCIPI