Abstract. Ibo LK, Arimukti SD. 2019. Ethnobotany study in Batak Toba sub-ethnic community in Martoba Village, Samosir District, North Sumatra. Pros Sem NAs Masy Biodiv Indon 5: 234-241. Samosir District is one of the areas developed as the Toba National Tourism Strategic Area. This program is carried out continuously, one of the goals is to improve the economy of the community, especially through the tourism sector. With this program development, infrastructure development and improvements continue to be carried out in several areas in Samosir District. This development will certainly have impacts on the community, such as the occurrence of modernization in people's lives. There are also some other problems that might arise such as economic pressure, population increase, and socio-cultural aspect. Besides that, new regulations that occur in the area are feared that it can result in the loss of local knowledge of the Batak Toba sub-ethnic community in Samosir District, one of them in Martoba Village, Simanindo District. Ethnobotany approach was conducted in data collection of local knowledge about the plant utilization in Martoba Village. Data was collected through an emic and ethical approach, including interviews, observation and inventory. Interviews were conducted with 5 key informants and 20 respondents. The result of the study shows that there are at least 98 plant species that are recognized and utilized by the local community. The most widely used plants belong to Malvaceae, Leguminosae, Compositae, and Poaceae. Based on its utilization, most plants are used as traditional medicines (52 species), food (19 species), and building materials (12 species). The most used part of the plant is leaves.