This study investigated whether the market response to replacement of CEO was significant according to the CEO structure and the ownership of CEO. The results of this study are as follows. First, as a result of analyzing the market response to the CEO's structural change, a significant negative market response was showed before the event when it was changed from a co-CEO to solo CEO. Second, in case previous CEO's performance was good, but CEO was replaced, it showed a significant negative market response. Finally, as a result of considering the CEO structure and ownership of CEO at the same time, there was no significant market response in most cases, but a significant positive market response was found when a solo CEO who owned more than 5% of the stock was replaced by a CEO who did not own more than 5%. This study contributes to providing evidence that market participants have an important understanding of the managerial structure.