Data retrieval system using secondary information of primary data to be retrieved as retrieval key

A data retrieval system capable of carrying out the retrieval using the secondary information of the primary data to be retrieved such as environmental information or structural information as the retrieval key. In the system, the primary data which are filing target to be stored and retrieved are stored in a first memory while secondary information associated with the primary data, which are not directly related with data content of the primary data, are stored in a second memory in correspondence to the primary data stored in the first memory. Then, when a retrieval key specifying a desired retrieval of the primary data from the first memory is entered, the secondary information is selected from the second memory in accordance with the retrieval key, and the primary data corresponding to the secondary information selected in accordance with the retrieval key is retrieved and outputted as a retrieval result.