This study examines the relationship between the president and the National Assembly in the current South Korean constitutional system from the perspective of neo-institutionalism. According to research findings, although the constitutional system of South Korea is close to the U.S. presidential system, the powers wielded by the president of South Korea are nevertheless greater than those of his/her U.S. counterpart. In terms of the institutional design, the unique single-term system, the absence of the position of vice-president and the role of the premier all impose further institutional restrictions on the exercise of power by the South Korean president. Under the influence of special regional considerations and political party structures, it often occurs that "the ruling party has a minority of seats while the opposition party has the majority of seats" in the South Korean National Assembly, which enables the opposition to resist the president by exercising its power to approve the appointment of the premier, to initiate impeachments and prosecutions, as well as to paralyze the National Assembly. Once the president no longer enjoys majority support in the National Assembly, a political stalemate is inevitable.