The purpose of this study is to present a rational explanation and future prospect of North Korea’s diplomacy over the past 30 years. Through this, it reasonably suggests the way of the denuclearization of North Korea and the dismissal of US sanctions against North Korea for meaningful progress in the on-going negotiations of the two. The factors that determine the future changes such as North Korea’s denuclearization desired by the international society are not the regime’ intention (state level factor), nor the top leader Kim Jung Eun’ decision making (individual level factor). Rather it is North Korea’s response mechanism coming from system constraints (yystem level factor) that determine such changes. North Korea is not an active decision-making body in the Uni-polar world system led by the United States in the post-Cold War era. The US and its allies must recognize it for the progress in the future negotiations on peace settlement on the Korean peninsula.