Underserved area is a region that has a lack of healthcare resources. In the context of Korea, however, there are not enough detailed criteria for underserved areas. In this study, we aimed to develop indicators for underserved area through Delphi technique. We systematically reviewed the existing measure of underserved area. Sixty indicators were extracted as candidates across four domains in secondary medical care. Four domains are demand, medical resource, quality of care, and health outcome. To develop indicator, two round Delphi survey was conducted among 15 professional experts such as professionals and public administrators. In conclusion, 2 final indicators (accessibility, medical utilization) was determined as an appropriate measure in order to designate underserved area for secondary medical services. Using our criteria from Delphi technique, 36 areas were found as underserved areas for the secondary medical care.