Purpose. This research aims to analyze the level of economic efficiency of cassava farming and the determinants that affect the efficiency level in the Wonogiri Regency, Indonesia.
 Methodology / approach. The research location was determined using the stratified random sampling method, and three sub-districts were selected in Wonogiri Regency, namely Ngadirojo, Jatiroto, and Puhpelem. Furthermore, this research used a random sampling method with respondents of 74 monoculture cassava farmers. The analysis method was the Data Envelopment Analysis (DEA) approach to analyze the economic efficiency of cassava farming and Tobit regression to analyze the determinants that affected it. Furthermore, primary data was obtained from respondents through interviews, and secondary data as a complement was obtained from relevant agencies.
 Results. This research showed that the level of economic efficiency (EE) of cassava farming in the Wonogiri Regency was 68.3 %. From the results of economic efficiency, there was an opportunity to improve efficiency by reducing input inefficiency by 13.1 % and minimizing input costs by 21.1 %. The determinants of factors that affected cassava farming were considered from the socio-economic factors, namely experience, educational level, and participation of farmers in farmer groups. 
 Originality / scientific novelty. Studies on the effectiveness of cassava have never been conducted in Central Java, even though Central Java is one of the three centers of cassava production in Indonesia. The efficiency of farming cassava in this research was not only considered from the technical side but also from the allocative and economic side, as well as the socio-economic character of the farmer’s environment. This research analyzed the efficiency of cassava farming with a nonparametric approach, namely Data Envelopment Analysis. Usually, efficiency research is approached with parametric analysis, namely production function analysis with Stochastic Frontier Analysis (SFA).
 Practical value / implications. It is recommended to use optimal inputs, especially seeds and fertilizers, which can be applied in cassava farming to reduce inefficiency. The need for fertilizer is related to the land’s condition, where the land in Wonogiri Regency has a steep slope, making it prone to erosion and sedimentation. Then, it affects the decline of the soil layer and the need for fertilizer. The role of the government is required because it is necessary to facilitate access to farmers and provide information about input use.