The number of North Korean defectors has increased from the 1990s. This phenomena has sought some significance as the reunification of the Koreas is being considered. It can shed insight on problems of socio-psychological adaptation. The dynamic process of the defectors' adaptation to the South Korean society may model a process of adaptation needed on a wider scale of and when reunification of Korea is achieved. North Korean defectors in South Korea are experiencing various difficulties in the capitalist society of South Korea including different value, identity problem, difficulties of social life, economic unrest, and psychological and emotional uneasiness. In this study, their problems and difficulties are analyzed for developing adaptation process. The process of adaptation for defectors can be divided into four stages: pre-awareness, awareness, adaptation and settlement. Particularly, mental and psychological difficulties are stumbling blocks to their adaptation. They need education for social adaptation and counseling programs. In fact, many South Koreans do not understand the North Korean defectors' difficulties in their process of adaptation. South Korean people need to accept North Korean defectors as their brothers and sisters, as persons of the same nation. Reunification is not restoration of the original state before the division. True reunification is to restore a broken relationship between the North and South.