There were several corporate frauds occurred in the years following the 1997 Asian financial crisis. The controlling shareholders expropriate minority shareholders’ interests by non-arm’s length transactions and tunneling activities. The expropriation by controlling shareholders is an issue for the corporate governance in Taiwan. This study collects the violations of related party transaction (RPT) rules and investigates the market reactions to the announcements of the fines on such violations. The sample period is from 2005 to 2014. The empirical results show that the abnormal returns are not significantly different from zero. To further focus on the sample of violations which the fine amount is greater than NT$1 million, the stock prices materially depress on four days before the announcement day, implying the negative information is released by insiders. Finally, this study proposes some suggestions on the market regulations.