This research focuses on analyzing the work of Carroll Monsignor, a missionary who spent most of his life in Korea after arriving in August 1931. In particular, the circumstances of his humanitarian work and its significance will be discussed in the context of the 1940’s and 50’s, being the height of the cold war. Carroll Monsignor’s missionary work can be said to have two fundamental principles. First of all, he believed in a pro-active approach of helping things pertaining to the body for spiritual salvation. He held that kindness done for the body was an effective method to open the heart of the soul. Thus his emphasis on loving actions naturally led to active humanitarian work. Furthermore,he believed in reverence for the Korean martyrs. Carroll Monsignor reiterated the fact that Korea was a place where the blood of martyrs had been shed, and accordingly devoted towards Korea as his place of ministry. Carroll Monsignor’s humanitarian work mainly focused on war refugees from North Korea, and the victims of the April 3rd struggle in Cheju. He expressed his hatred for communists by calling them demons, but he actively helped their victims, the war refugees from the North. He outrightly detested Communism, to the point where he became a target of Communists, but his anger was directed against the leaders of the Communist regime. This can indeed be seen from his humanitarian work for war refugees as well as prisoners of war. The April 3rd struggle in Cheju was a bloody massacre that began in April of 1948 to September 1954, lasting for about six years and six months. In particular, in the four months following November of 1948, tens of thousands of people were massacred in 130 out of 160 towns. While Seung-man Lee was utilizing every method available to oppress Cheju, the Monsignor visited Cheju and carried out his humanitarian work in dozens of towns. When Father Sweeney, Augustine J. (1901~1980) wrote a letter decrying the situation of Cheju, Carroll Monsignor showed the letter to the American embassador and Seung-man Lee. He also reported on his activity in Cheju to the Maryknoll by photographs and a written account. Thus, it is assumed that Carroll Monsignor and Seung-man Lee already mutually shared an uneasy sentiment. Lee, Seung-man and Carroll Monsignor’s relationship with worsening gradually. Carroll Monsignor’s activities and Lee, Seung-man’s policies were at constant odds with each other, for Carroll Monsignor extended his humanitarian aid towards North Korean refugees and also reported on the true situation of Cheju. Furthermore, Carroll Monsignor also disagreed with Lee, Seung-man on the issues of the Busan political scandal, the return of POW’s in Geoje island [巨濟島] POW camp, and the aid for those wounded in action. Carroll Monsignor also was quite close with minister Chang, Myeon (張勉, 1899. 8. 28~1966. 6. 4.), a political rival of Seung man Lee. However, in the course of his humanitarian work, Carroll Monsignor did not divulge his political beliefs nor did he help only the Catholic. To Carroll Monsignor putting forth the name of religion or the missionary conference he belonged to was not of great importance. Due to the Korean war, aid for the everyday Korean people was harshly insufficient, while the American aid was focused around militaristic aspects.Thus Carroll Monsignor’s humanitarian aid was significant to Korean society in that it overcame distinctions of ideology and religion. As such, Carroll Monsignor was a missionary and social activist beyond ideology and religion, who emphasized the necessity of a pro-active attitude for the salvation of souls in a difficult time like the Korean War.