ABNORMALITY DIAGNOSIS SYSTEM

An abnormality diagnosis system 1 for diagnosing an abnormality event in an atomic power generation plant on the basis of an abnormality indication detection result from an abnormality indication monitoring system 5 is provided with: an abnormality diagnosis control unit 11 which acquires a parameter transition in a monitoring period from a non-detection timing to an indication detection timing, and a parameter contribution in the monitoring period; and a database 10. The abnormality diagnosis control unit 11 executes a matching determination between the parameter transition and parameter contribution that have been acquired from the abnormality indication monitoring system 5, and a parameter transition for determination and a parameter contribution for determination that have been stored in the database 10, and identifies an abnormality event and an abnormality indication facility that are associated with the parameter transition and parameter contribution determined to be matching.