This study aims at investigating the implementation process of electronic network systems in Japanese large firms, focusing on the innovativeness among industries to which firms belong. The electronic network systems such as Local Area Network (LAN) have spread rapidly during last several years. Accordingly, many firms in Japan have introduced them in their organizations. After the advent of the computer invention, computer and telecommunications technologies have merged into information technology, making a remarkable progress constantly for several decades. The electronic network systems are a kind of information technology, going back to 1950s when data communications systems were first developed. In the beginning were these systems managed by professional people. However, due to the rapid progress of the information technology, even untrained people who have no specific knowledge about IT or do not belong to the IT section have been able to use the electronic network systems in business organizations since the late 1980s. In addition, especially with the appearance of multimedia systems and the expansion of the usage of Internet, many organizations have begun introducing electronic network systems since 1990s. For this study, we sent questionnaires in 1996 to Japanese large firms in which they employed more than 1000 people. Based on the results and the interviews made in connection with this research work, we analyze first the state of the introduction of the electronic network systems, focusing on the innovativeness of firms. Next, we examine why the electronic network systems have come into wide use among Japanese large firms.