Research on the lives of overseas Taiwanese in the state of Manchuria or Manchukuo (滿洲國) in the Japanese colonial era has been scarce. This study is a pioneering attempt to explore the history of this period through reviewing the life of the highest-ranking official originally from Taiwan. Hsieh Chieh-shih (1879-1954). Hsieh, a Taiwanese native from Hsinchu, was the first Foreign Minister of Manchukuo as well as its first ambassador to Japan. This paper traces the life of Hsieh, his early activities, his role in the restoration attempt of Chang Hsun (張動), and his service to the last Qing emperor Pu-i. During his tenure as Manchukuo's Minister of Foreign Affairs, Hsieh had to deal with the investigation team from the League of Nations and establish relationships with other countries. As ambassador to Japan, Hsieh represented Manchukuo at the Taiwan exhibition of the fortieth anniversary of Japanese colonial rule of Taiwan (台灣始政四十周年記念博覽會) held in October 1935. Having retired from official duties, Hsieh served as the director of Manchu House Property Company (滿洲房産株式會社) and moved to Beijing. Alter the Second World War. Hsieh was charged of treason and put jailed. He was released in 1948. Over the course of his life, Hsieh had different nationalities and identities. He was born in 1879 during the Qing Dynasty, recognized as a Japanese subject in the colonial era, became a national of the Republic of China in 1915, and changed again to become a Manchurian in 1932. What do his changes in nationality and identity say about changing loyalties? In sum, the life of Hsieh, with all its twists and turns, serves as a good starting point for understanding the activities of overseas Taiwanese in Manchukuo in the Japanese colonial era.