When you think of Nagasaki, city where the atomic bomb was dropped, it is usually described as passive and accepting about the atomic bombing compared to Hiroshima. Even despite to the peace treaty of Hiroshima and Nagasaki being declared on August 6th and August 9th respectively, Nagasaki has a passive voice for political views on the atomic bombing. That is how the saying, “Angry Hiroshima, Praying Nagasaki.” A lot of Christians lived where there when the atomic bombing was held. The damage was fatal, causing many casualties, although the believers of the emperor conceived it as a punishment from God and started discriminating, humiliating, and scorning the bereaved families who were exposed to radiation. The person who fought against this is Nagai Takashi (1908-1951), a doctor and professor, also Christian, who accepted the exposure as God’s will. This led Nagasaki to be called the city of prayer, however, it is giving indulgence to Japan’s war responsibilities and the U.S.‘s dropping of the atomic bomb. Regarding critical introspection of the war responsibility, Oka Masaharu (1918-1993), a pastor, a city council member, a civic righter, and the plaintiff of the unconstitutionality suit to the monument to the war dead, strongly criticized the nationalism of the exposed brought from emphasizing themselves as the only country exposed to radiation even with their atonement for it. In order for Nagasaki to become a true city of peace, the idea shift from Nagai Takashi to Oka Masaharu should need to occur. That is why this thesis observes and compares specifically on the two’s lives and ideas especially on their understanding of the U.S.‘s dropping of atomic bomb, the Japanese emperor, war responsibilities and their perception of the Nanking Massacre, and lastly their opinions on nuclear power. In conclusion, the ideas of the two have been verified totally different from each other, and in order for Nagasaki to become a city of peace, it should pursue and implement the idea of Oka Masaharu as quickly as possible.