Information transparency has been a necessary device in the activities of corporate governance. Especially, whether the presentation of information at corporate web sites is transparent plays a unique role on corporate governance for the era of knowledge-based economy. In this regard, this study examines what factors influence firm’s internet disclosures in terms of three dimensions: insider ownership, corporate characteristics, and outsider ownership. The aim of doing so is to provide an indication for government regulators, corporate executives, investors, and interest groups to strengthen corporate governance mechanism. The empirical results revealed the following facts. In considering insider ownership, the more/less shares the majority shareholders/supervisors hold, the less transparent in corporate information disclosure. In considering corporate characteristics, companies with high degree of leverage, large number of employee and operating in the IT sector tend to disclose information profoundly. In considering outsider ownership, companies with high holding-ratio by public sector, domestic banks, and institutional investors would disclose information more detailed. Due to this study was conducted before the results of information transparency review issued at the first stage, the factors affecting companies on voluntary information disclosure were observed without interference of mandatory requirements. Consequently, the evidences drawing from this study could be clues to existing review indicators for further modification. Hence, the control of corporations’ operation might be more exact and prompt so that the investors and related parties’ rights are protected.