A safety assessment apparatus comprising: a database storage that stores an original database composed of a plurality of records and a secure database that conceals the original database; a neighbor record search part that obtains, for each record in the secure database, a neighbor record set having a predetermined neighborhood number by a neighbor search of the original database; a duplication exclusion part that acquires a deduplicated neighborhood record set from which duplicate records in the neighborhood record set are eliminated when a number of records in the neighbor record set is greater than a predetermined threshold value; a nearest neighbor record calculation part that calculates, for each record in the secure database, a distance from each record in the deduplicated neighborhood record set when the number of records in the neighbor record set is greater than the threshold value, and that calculates, for each record in the secure database, a distance from each record in the neighbor record set when the number of records in the neighborhood record set is equal to or less than the threshold value, and obtains a nearest neighbor record based on the distance from the record; a re-identification determination part that calculates, for each record in the secure database, a re-identification rate of the record based on whether a record in the original database corresponding to the record in the secure database matches the nearest neighbor record; and a re-identification rate calculation part that calculates a re-identification rate of the secure database based on the re-identification rate calculated for each record in the secure database. a database storage that stores an original database composed of a plurality of records and a secure database that conceals the original database; a neighbor record search part that obtains, for each record in the secure database, a neighbor record set having a predetermined neighborhood number by a neighbor search of the original database; a duplication exclusion part that acquires a deduplicated neighborhood record set from which duplicate records in the neighborhood record set are eliminated when a number of records in the neighbor record set is greater than a predetermined threshold value; a nearest neighbor record calculation part that calculates, for each record in the secure database, a distance from each record in the deduplicated neighborhood record set when the number of records in the neighbor record set is greater than the threshold value, and that calculates, for each record in the secure database, a distance from each record in the neighbor record set when the number of records in the neighborhood record set is equal to or less than the threshold value, and obtains a nearest neighbor record based on the distance from the record; a re-identification determination part that calculates, for each record in the secure database, a re-identification rate of the record based on whether a record in the original database corresponding to the record in the secure database matches the nearest neighbor record; and a re-identification rate calculation part that calculates a re-identification rate of the secure database based on the re-identification rate calculated for each record in the secure database. <EOS>