With the recent increase in the number of operating nuclear plants, the need for automatic collection of water chemistry control data, computer processing, and data assessment and diagnosis are increasing. To fulfill these needs, a water chemistry general management system is being developed. As part of this program, an automatic metal analyzer has been developed, andfunctional verification tests have been conducted at an operating boiling water reactor plant. It is very difficult to automatically sample metal impurities in cooling water since they are usually analyzed after being collected in a filter. With this automatic analyzer, however, metal impurities can be analyzed continuously by ion-exchange chromatography after being heated and dissolved. The measurement results confirm that analysis of iron, nickel, copper, cobalt, etc., is possible at a minimum detection limit of 0.01 ppb. It is possible by this means to construct an in-line automatic analysis system for a nuclear reactor primary system. Used in combination with a water chemistry diagnosis system, this will improve the measures for preventive maintenance employed in nuclear power plants.