Manufacturing management information relating to a module battery and single battery mounted therein which are obtained in a battery manufacturing process (1) is collected by a manufacturing quality information collection processing unit (4) and stored in a database (6). In a battery diagnosis system (3), when the module battery (2) under a usage environment is charged, an operation result processing unit (5) collects operation result information relating to the module (2) and stores the operation result information in a database (7). An operation result monitoring processing unit (8) determines whether the operation result information is abnormal, and supplies the result of the determination to a manufacturing/usage environment factor classification processing unit (9). When the result of the determination indicates that the operation result information is abnormal, the manufacturing/usage environment factor classification processing unit (9) diagnoses, on the basis of the manufacturing management information relating to the module battery in the database (6), whether the abnormality of the operation result information is caused by a manufacturing factor or a usage environment factor, and the result of the diagnosis is created and displayed by the diagnosis result creation processing unit (10).