The purpose of this study is modeling a user-friendly Korean-Japanese thesaurus for internet circumstances. The methodology had two steps: first, the problems were analyzed when multilingual thesaurus is constructed, with review of various multilingual thesauri and interview with multilingual thesaurus constructor in Korea and Japan. Second, collaborative tags were analyzed to differentiate cultural/linguistic background from word usage pattern. As a result, searching thesaurus model was suggested and applied to develop a user-friendly Korean-Japanese thesaurus.