The purpose of this study is to provide possible suggestions in order to promote online transmission service of digital works and the construction of digital libraries. To achieve this purpose, the definition, and characteristics of digital library were reviewed. And the current status of information service of digital libraries in Korea. Japan, and U. S. was examined. The regulations relating to online transmission in digital libraries on the copyright law revised in December 1999 were understood. As a result, this study suggested the establishment of center to manage the reproduction and online transmission of digital works collectively. And it also suggested the introduction of technical measures to protect copyright.