Modern public library is expanding its role as generalized cultural facility. Therefore public library that has comfortable and physical environment for various age and various users are needed. The purpose of this research is to evaluate the application of universal design in common space of public library, and trying to suggest environmental improvement plan that various users could comfortably use the library based on its data. The scope of this research were adjusted as 8 public libraries located in Seoul and metropolitan area of Seoul. Spacial scope that was set of this research was common space of public library and scope of content was about application of universal design. As a result of the research, first, the application of universal design toward common space of public library were appeared as low. Second, constant management and application development of universal design is needed. Third, as roles and functions of public library become various from now on, application of delicate universal design is needed for intention of users.