The research aims to measure cost efficiency and identify the factors affecting cost efficiency on sericulture in Roi-Et and Mahasarakham Provinces as well as comparing farmer's management performance between high-efficiency and low-efficiency group. The findings of the research can provide the guides to increase the cost efficiency. Data are randomly collected from the farmers who operate sericulture in Roi-Et and Mahasarakham in the year 2007. The samples are 210. Data analyses are composed of Stochastic Frontier Analysis (Cost Frontier), Tobit Regression, and mean comparison with t-statistic. The result appears that cost efficiency (CE) equals to 98.88% and major causes of cost efficiency are management performance and credit from Bank for Agriculture and Agricultural Cooperatives (BAAC). The management performance on the high-efficiency group being greater than the low-efficiency group are planning, organizing, leading, and controlling. To improve cost efficiency, the low-efficiency group could learn how to manage their production and management performance from the high-efficiency group. © International Economic Society.