Abstract: In a data management system of this invention, data elements to be registered are managed by item information records each comprising a name of the data element, an item code corresponding to an item to which the data element belongs, and a serial number. The relation between item information records is managed by a relation information record expressed by a source item ID, an object item ID, an item code associated with a source corresponding to an item, and a relation ID indicating the relation between the source and object items. The relation ID is given by a relation table. When a search instruction is input, the item information record, the relation information record, and the relation table are referred to, thus obtaining item information to be searched. The item formation record and relation information record can be registered as needed.