Although the contents of the inter-Korean economic cooperation agreed at April 27, 2018 Panmunjom Declaration and the September 19, 2018 Pyongyang Joint Declaration were compromised at the lowest level, it may still be a problem whether the UN Security Council's sanctions against North Korea would be violated. In other words, as long as sanctions for the UN Security Council are maintained, it may be difficult for the inter-Korean economic cooperation to resume at the agreed level. The problem is that even at the level of economic cooperation that has been agreed between the two Koreas, it is not enough to make North Korea a blue ocean for Korean economic revitalization and to bring about North Korea's denuclearization efforts. In this article, we examined the possibility of compatibility of the inter - Korean economic cooperation and the resolutions of the UN Security Council against North Korea, as well as the probability of violation of the UN Security Council sanctions resolution at the resumption of inter - Korean economic cooperation. It will be possible to ask the sanctions committee to approve the transaction of goods and financial support for resuming inter-Korean economic cooperation, and to explain the strategic necessity of resuming inter-Korean economic cooperation and induce the sanction committee to approve it. I have reviewed the domestic law on ROK's sanctions against North Korea and thought about ways to improve ROK's domestic implementation law by referring to the way in which major foreign countries have implemented the resolution of the UN Security Council. Inter-Korean economic cooperation has been suspended due to the "5·24 Measures", which was announced in the form of a statement by the chief of the Office of the President of the Prime Minister 's Office in 2010. As we try to resume now the inter-Korean economic cooperation once suspended, we have found that there are more international and domestic legal difficulties than before, and we have to solve them. In order to guarantee the legal stability of inter-Korean economic cooperation in the future, it is necessary to revise the relevant domestic laws so that inter-Korean economic cooperation can not be easily interrupted by domestic measures with ambiguous legal status and non-binding power. Lastly, the United States’s sanctions against North Korea, which had operated separately from the UN sanctions, were examined. If the US President designates the suspicious enterprise which is alleged to have been involved in economic cooperation with North Korea, the legal consequences (secondary boycott) and the negative economic impacts upon the specified entity will never be light. The operator of foreign ports and airports which do not strictly oversee the vessels and aircraft to travel to North Korea will be subject to sanctions and they will be reported to Congress. Therefore, it is assumed that the ROK can finally resume the inter-Korean economic cooperation only when it can accommodate resources to exert diplomatic efforts towards North Korea’s denuclearization and it can rely on the United States’ and international community’s genuine cooperation eventually.