ABSTRACT Hanif Harahap (1104134), Sosial Revolution in Simalungun 1946. Thesis. Graduate Program of State University of Padang. This research aims to trace the factors that led to a social revolution in Simalungun. It also searching for find out the process of social revolution going on, as well as the impact of the social revolution in the Simalungun social structure. The researcher used several documents from the Algemeen Secretarie en de Daarbij Gedeponeerde Archieven 1945-1949 as a primary source in this research. In addition, researchers also use contemporaneous newspaper that covered the event complete social revolution that occurred in Simalungun, such as Merdeka, Boeroeh and Ra‟jat. There are few living witnesses of such events can be interviewed as informants like Nasir Purba, Abdul Rahman Purba, J. Saragih, etc. The data has been obtained, performed source criticism, analysis-synthesis, interpretation and explanation of the history and writing a research report. The research showed the following findings; social revolution in Simalungun is a change of soscial structur with a criminal act that based on sentiment and personal vendettas group of people. Resentment arises due to oppression and domination of the Raja to the people. The entry of the plantation capitalist system in to Simalungun widen the socioeconomic gap between the Raja and the people. Plural society who created by Netherland Oost Indies government through the mobilization of the Tobanesse came to Simalungun as well as efforts to bring the Javanesse to Simalungun for the plantation requirements, causing social friction led to a social revolution. During the Japanese occupation a surge peaks pique people to the Raja, because the Raja cooperation with Japan in the suppression of the people. During the Japanese occupation of the people is also provoked the Japanese to destroy all the powers associated with the Netherlands and the Allies. After the independence of Indonesia, Xarim M.S., and the other Marxists‟ leader in East Coast Sumatra mobilize the Simalungun youth to make a social revolution the Raja. The impact of social revolution in Simalungun, the Raja that survived have loss his power, rights, meaning and function. Instead of people taking power and rights of Raja.