Abstract: A data exchange system among in which data is mutually exchanged among cooperative companies which produce products cooperatively, provides for periodically collecting or retrieving at least one of product progress information, quality information, and business information of one's own company, standardizing and editing data for transmission to the cooperative companies, exchanging data between one's own company and the other companies, outputting transmission data to a file in a fixed format as attached data of an e-mail, automatically and periodically transmitting the e-mail to the cooperative companies, and receiving e-mail corresponding to the transmission data from the cooperative companies.