Abstract: A network system having a plurality of databases wherein data are respectively stored, a plurality of terminals for use in retrieving data in the databases, a plurality of connecting devices for connecting the databases and the terminals, and a control unit for giving data-caching instructions to connecting devices selected on the basis of the results of analysis of data concerning access logs with respect to the databases. When a demand for data retrieval is made from a terminal and when data to be retrieved exits in a connecting device that has received a data-caching instruction, the data is made the result of retrieval. The analysis of data concerning an access log is made at predetermined time intervals.