The diffusion of online corporate issues (news and rumors) is becoming a critical factor in corporate reputation management. As they spread very fast and broadly, it is difficult for a corporation to respond to them effectively. Therefore, this study focuses on exploiting the origination and diffusion patterns of online corporate issues to provide practical implications to a corporation. In doing so, we selected the sample cases (2 news and 2 rumors) and analyzed their contents, initial sources, diffusion paths, and the actions which the corporations actually took. Finally, we drew 6 propositions. Proposition 1-1: The issue originators have a tendency to solve the problems they have after failing to make a compromise with the corporations. Proposition 1-2: The distrust in a corporation facilitates the origination of online corporate issues. Proposition 2-1: Online corporate issues are largely originated from the communities with high level of anonymity. Proposition 2-2: Online corporate issues spread through online communities or portals and get a public confidence by a mass media’s acknowledgment. Proposition 3-1: Netizens have a tendency to come around others’ opinions easily rather than to discriminate truth from falsehood. Proposition 3-2: Once online corporate issues are spread massively, it is difficult for a corporation to respond to them successfully. Additionally, this study provides three implications to a corporation: First, enhance the monitoring activities to online corporate issues. Secondly, take a prompt action to negative online corporate issues. Lastly, build the feedback systems to reflect consumers' opinions.