By having a file data storage section that stores file data of a file; a management information storage section that stores management information identifying the file, the management information being related to the file data; a control information storage section that stores control information on a file to be blocked on which a predefined specified processing is to be executed; a management information retrieval section that retrieves the management information stored in the management information storage section; a control information retrieval section that retrieves the control information stored in the control information storage section; an execution section that, when the management information retrieved by the management information retrieval section corresponds to the control information retrieved by the control information retrieval section, executes the predefined processing on the file data related to that management information, proliferation of an important file distribution of which should be restricted over a network can be restricted.