The purpose of this paper is to clarify the transformation of end users, who utilize information technology to become innovation leaders as they demonstrate user innovation and at the same time exercise strong influences on the spread of innovation and make it an integral part of society. In order to achieve the objective, the author examined the transformation process in phases from two perspectives. The first perspective, which concerns the spread of innovation, examines the influences that end users exercise on the market by making the most of information technology to form a virtual user community. The second perspective, which relates to product reform by end users, examines the process in which, after co-innovation with provider companies, end users become independent through absorbing know-how and investments and dominate the market as creators of innovation. The case studies conducted from these two perspectives clarify that end users are market leaders who use information technology effectively to display their competitive advantage eventually, and that this tendency is similarly observed whether they are consumers or enterprises. These studies also indicate that information technology changes not only products but also entities that dominate the market.