Many people have often questioned the independence and effectiveness of outside directors in chaebol (conglomerate) companies. Because the Korean Commercial Act requires that at least 50% of the board of directors (for companies with total assets of 2 trillion won or more) be composed of outside directors, Korean companies must fill a considerable number of board seats with outside directors. However, the future performance and various management policies of a company can differ depending on which outside directors are appointed. According to an article reported by the JoongAng Ilbo in 2012, professors account for more than 35% of the board members of Korea's top 10 companies. Professors have traditionally been regarded as suitable candidates for outside directors in Korean society because they are considered independent and possess professional expertise. However, no research has been conducted on whether these professor-outside directors effectively monitor and advise management as outside directors. A small number of researchers in the United States have studied the role of professor-outside directors but have failed to reach consistent conclusions regarding the role of professor-outside directors in corporate management (White et al., 2014; Francis et al., 2015). The contribution of this study lies in examining the impact of professor-outside directors on corporate governance, focusing on Korean chaebol companies where corporate governance is a critical issue. In this study, we investigated the effect of professor-outside directors on firm value and the characteristics of firms that appoint professor-outside directors. We also analyzed the monitoring function of professor-outside directors using performance-CEO turnover sensitivity, performance-executive compensation sensitivity, and earnings management behavior. The empirical results showed that professor-outside directors have a negative impact on firm value, which is attributable to the fact that firms with professor-outside directors do not exhibit high performance-CEO turnover sensitivity or performance-executive compensation sensitivity, and are vulnerable in monitoring earnings management. In summary, the empirical results of this study indicate that professor-outside directors do not play a significant role in improving corporate governance.