Recently in the Korean society, there has been an active expansion of discussion on the issue of hostile M&As. In Korea, the issue that is of most concern is the M&A of domestic enterprises by foreign capital. The purpose of the study is to estimate the effectiveness of foreign capital regulation in Korea as a defensive mechanism of hostile M&A. Hostile M&A, started in 1994 and have been open to foreigners since February 1998, when most of the regulations for foreigners were relaxed. This study shows that Korean regulations for foreign capital are effective in terms of deterring foreign hostile M&A. (The rest is omitted.)