Subak constitutes a traditional irrigation system in Bali which has a nature of socio-agrarian-religious based on the culture and Hindu religion in Bali. Farming culture in the subak system is one of the cultures supporting the development of cultural tourism in Bali. Since 2012, UNESCO has recognized the existence of subak as the world cultural heritage. The economic growth of development often results in impacts that are less favorable for agricultural development, such as conversion of rice fields. The government of Denpasar city has introduced ecotourism within subak. The objectives of this study are to: (i) find out the problems encountered by subak related to ecotourism; and (ii) describe the extension techniques that are carried out for the development of ecotourism within Subak of Sembung. This subak was selected by purposive sampling.  is in Subak of Sembung, Peguyangan Village. Key respondents were selected to get data needed. Data collected by using interview, survey, observation and documentation. Descriptive method was employed to analyzed data. The study pointed out that there are some problems encountered by subak in the development of ecotourism, such as the aspects of production, tourism education, and business management. Therefore, it is needed the empowerment of subak to overcome the problems faced. The increase of crop production (corn, chili, eggplant, long beans, vegetables, cucumbers and also papaya) is carried out through direct extension and training activities in their rice fields. Improvement of tourism education is also done through the extension activities for the subak members and management board of traditional village and the ecotourism managers, especially those concerning sapta pesona (seven of charm). Strengthening of farmers’ capacity on business management is conducted through the extension training about post-harvest, such as processing, packaging, and marketing. It could be suggested to the subak and managers of ecotourism and traditional villages to have better synergy of their activities to ensure the sustainability of the development of ecotourism of Subak of Sembung. Government should support ecotourism activities through the promotion of the existence ecotourism within subak.