To smoothly execute the maintenance work of a data base server during on-line operation without stopping the on-line processing.

Each application server of an application server group 2 is provided with a storage area which records the operating situation of a present data base server group 3, and in an execution process for executing an application program corresponding to an application processing request received from the client group 1, a data base operation request included in the application program is processed by using the data base server searched from the operating situation. A server managing terminal 6 is used at the time of changing the operating situation of any data base server belonging to the data base server group 3 for the maintenance or failure monitor of the data base server.