In a source file for a server, a Web display control division, a CGI script division and a processing program division are separated.The server has a Web server division, a CGI script control division and a processing program division and constitutes an interactive system together with an operation terminal unit in which inputs are made through a Web browser. A display control file describing Web page control information is provided for each Web page to be displayed, and the CGI script control division analyzes the description of the said display control file designated by said Web browser, executes said processing program following the description and outputs the result of the processing from Web server division to said Web browser. The name of processing programs activated for collection of information for the display of a Web page and control of the system and a method for displaying the result of such processing on the Web page are described in a script format in the display control file.