South Korea and North Korea relation becomes one interesting topic to be discussed, as both Korean states shared a common culture, language, and even history together. From years to years, South Korean has been adapting several different foreign policies toward North Korea. In the past, South Korea implemented the soft-way approach named Sunshine Policy, which was applied during Kim Dae Jung administration and Roh Moo Hyun administration. Moreover, under Lee Myung Bak and Park Geun Hye era, South Korea was more referring to hard-line policy approach. Today, South Korea is under Moon Jae In presidential administration and under his administration, South Korea decided to implement Sunshine Policy again. After under some presidential administration did not implement anymore, Sunshine Policy is being implemented once again on President Moon Jae In era today. The objective of this research is to analyze the domestic politics aspect, military capability aspect, and international context aspect that influenced South Korea decision under Moon Jae In administration to reoriented on Sunshine Policy implementation based on William D. Coplin’s theory of decision-making process. Furthermore, in order to execute this research, the writer was using a qualitative method by using secondary data taken from sources such as books, journal articles, government publications and other literature sources. This research then revealed several findings that proved the existence of domestic politics, military capability, and international context as factors that influenced South Korea on Moon Jae In administration reorientation to Sunshine Policy. In domestic politics, the decision was influenced by Democratic Party of Korea and the personality of President Moon Jae In. Meanwhile, in military capability aspect influenced by the fact that South Korea has lower military capability compare to North Korea. Moreover, another factor was coming from the international context that influenced by the behaviour of North Korea in the past responding to Sunshine Policy.