In December 2004, the United Nations General Assembly adopted the "UN Convention on Jurisdictional Immunities of States and Their Property". This new convention has become the first international multilateral convention to deal with the problem of State immunity or sovereign immunity in a comprehensive manner. This UN convention is the product of continual international negotiations since 1978. The convention reflects a new trend of customary international law of State immunity from absolute immunity to restrictive immunity. The convention is based on the Draft Articles made by the International Law Commission (ILC) with a view to establishing the `rule of law` and `legal certainty` in the area of State immunity. The convention has not yet entered into force, but many States are now reviewing it for the purpose of ratification. In the case of the Republic of Korea, absolute State immunity theories were supported for a long time, but on December 17th, 1998 the Supreme Court of Korea took a different position based on restrictive immunity theories in a case in which a Korean citizen had filed a civil lawsuit against the United States with respect to an employment contract. The significance of this new UN Convention may be summarized as follows: ⅰ) the Convention enumerates eight cases in which the activities of foreign States are not immune from civil jurisdiction in the courts of the forum State. ⅱ) The Convention has eliminated the problem of uncertainty in customary international law of State immunity by means of providing binding written provisions in which States are not entitled to claim jurisdictional immunity with respect to particular activities. ⅲ) As the Convention has made the scope of possible exercise of legal jurisdiction before municipal courts clear, it appears likely to prevent the occurrence of various disputes between and among countries in advance, by way of consolidating the principle of `rule of law`. Moreover, as the Convention contains provisions in which the contents of State immunity are clearly codified, the long-standing problem of ambiguity in this area may be resolved. `Legal certainty` between parties(government and foreigners) in international business transactions would be better guaranteed as well, because the Convention can serve as a standard for expected results of future transactions, thereby increasing the predictability of international business transactions. ⅳ) The Convention would contribute to stimulating international business transactions on the whole. ⅴ) The Convention features an internationally binding agreement, not a simple model or framework law, and would function as a unified and comprehensive source of law in the area of State immunity under contemporary international law. ⅵ) Given that five outstanding substantive issues have been resolved by way of compromise, and thus there is room for flexible treaty interpretation and applicability in favor of each State, it is highly likely that most States will ratify this convention in the foreseeable future. For the Republic of Korea, this convention presents standards and guidance for legislative measures on the basis of restrictive State immunity theories. Granted that the Supreme Court of Korea has already produced a judgment in which restrictive immunity theories were implicit, the contents of the new convention would be beneficial to protecting Korea`s national interests. An enactment of relevant domestic law would be necessary, in this regard, as a way to enhance Korea`s national interests in international business transactions.