Most of academic research on office market has focused on large office buildings. Although compared to large office building, small and medium buildings have distinctive characteristics in location, tenant types, main use, owner types, and so on, there is little research on small and medium buildings. The purpose of this research is to analyze how small and medium building’s various features affect its Net Operating Income (NOI). For an empirical research, we collects real transaction data from 2009 to 2015 in Seoul and analyze these data by using multiple regression model. For a regression analysis, numerous features of the building have possibility to affect NOI, are categorized into trade area, location, site, building, tenant, management characteristics. The empirical research shows the NOIof small and medium building was affected by trade area, location, site, building, tenant, management characteristics. The regression analysis shows the trade area, location, and site characteristics such as proximity to main trade area, proximity to subway station, corner location, and zoning of site, have significant effects on NOIo f small and medium building. This study confirms building characteristics such as gross floor area, age of building, elevator installation, and proportion of leasable area to 1st floor gross area, have significant impacts on NOI. The NOI of small and medium building is also influenced by the tenant and management characteristics such as proportion of leasable area for commercial use to gross area, its vacancy rate, whether building is used for residential use or building owner, and its management fee charging system. Through this study, we can confirm the NOIof small and medium building is affected by different characteristics from large office building.