The purposes of this study are to examine the various methods of subject access in the rapidly changing environment and to suggest the future of subject access in National Library of Korea (NLK). First of all, current status and problems of Library of Congress Subject Headings List as an representative subject headings in the world and the ways of improving effectiveness of subject retrieval were dealt with. As the ways of improving subject access, social bookmarking, folksonomy, tagging, facet applications, automatic assignment of keyword, thesauri, classification system, and auto-assigned search box were suggested. Finally, current status of NLK subject headings and the ways of improving for utilization of the subject headings as subject access were provided.