What is the role of the United Nations in regard to nuclear and radioactive materials? Wasted radioactive materials, which were thrown by many countries, are one of the serious environmental problems in the world. All living things are seriously affected by these materials. We, as members of the international society, should solve this problem for the sake of sustainable development of natural resources. In addition, we also must work on the nuclear disarmament for the sake of non-nuclear weapon international society. The United Nations has a great role of dealing with such problems. Under the support of IAEA, the members of the UN can watch some countries’ illegal throw of radioactive materials and pressure the nuclear development of unadmitted countries such as Iran and North Korea. By the leadership of the UN, we can make these materials safer to use mainly for industrial activities, point out how dangerous the illegal throw of wasted radioactive materials and ask countries to remove them with as a safer method. In this way, the UN can contribute to keeping the environmental of the earth clean and beautiful. The UN, especially the Security Council, is where the great powers with nuclear weapons can gather and talk, which means the UN can give them good opportunities to think about the nuclear disarmament. The great powers tend to put their national interest before the disarmament, but the UN can continuously make them understand the risk of nuclear weapons. In this way, the UN is playing its role in regard to nuclear and radioactive materials.