This study sought to develop a social capital index that can contribute to good health in rural communities. A questionnaire was mailed to 7,114 residents of Village A aged 20 years and over in June 2016. A total of 1,327 questionnaires were returned; 4 unfilled forms were eliminated from the analysis and the remaining 1,323 were used to develop a rural community social capital index comprising 4 concepts and 16 items. The goodness of fit of the model was satisfactory, and comparison with other scales confirmed its validity. The model is also associated with the outcomes of self-evaluation of health, sleep status, elderly life competence, frequency of social outings, and Global Deterioration Scale score of 5, thus confirming its criterion-related validity. The reliability of the index was also good with a Cronbach's α value ≥ 0.80 for each concept and all 16 indices. The rural community social capital index developed in this study will help establish healthy communities. Studies of other rural areas are anticipated to accumulate research outcomes.