1. CONTENTS (1) RESEARCH OBJECTIVES This study seeks to find the business characteristics by industry that rent medium to large office spaces in Seoul. (2) RESEARCH METHOD First, it seeks to find the different characteristics in lessee composition of medium to large office buildings in Seoul. Second, it aims to understand the possibile interrelationship of locations between the industries in which lessee businesses are and to compare them. Third, it seeks to present a new standard that may be used in determining which industries are specialized in certain areas by reviewing the office space rented in three major office building areas of Seoul and the number of businesses in it. (3) RESEARCH FINDINGS The analysis showed that the average number of industries that the lessees of medium to large office buildings were engaged in was 6.5. The major lessees engaged in industries like banking and insurance, manufacturing, and wholesale and retail industries were found to use 40-49% of total office spaces and the other industries the remaining spaces. 2. RESULTS The findings showed that in CBD transportation, banking & insurance, public administration, defense industry, social securities and several other service industries were found to be specialized both in terms of office space rented and the number of businesses; and in YBD manufacturing, lodging and restaurant, health, social welfare services; and in KBD manufacturing, wholesale & retail, science, technologies services.