This study compared the perceptions of Korea, Korean language, and Korean culture between Koryoin and Joseonjok, who are the representative Korean diaspora, and examined the causes from various angles. In particular, this study conducted a survey of 66 Josenjok and Koryoin Korean teachers, who are required high knowledge and awareness of ethnic language and its culture both internally and externally. This study found statistically significant results that Joseonjok teachers have a higher Korean language and cultural efficacy than Koryoin teachers, while Koryoin teachers have more interest in Korea than Josenjok teachers. In order to find out where these differences were originated, this study examined various factors such as ethnic policy and language policy of their resident country, overseas Korean policy, and their status in Korea. Accordingly, this study presented the process of changing Korean Diaspora’s perception towards their home country dynamically.