This research aim to analyze the reasons for the approval of the United States Agreement toward Joint Comprehensive Plan of Action (JCPOA) related to Nuclear Iran in 2015. After 12 years through negotiations that difficult problems of uranium enrichment is owned by Iran find confluence. In the end, the path of diplomacy can prove that as hard as anything a problem can be resolved by negotiation and peace. The results of this research showed that the foreign policy of the United States to approve JCPOA constituted by the reasons favorable to the United States in the field of security, economy and politics.