Abstract
Rem Koolhaas is one of the most influential architects in his generation. OMA(the Office for Metropolitan Architecture) which was founded in 1975 by Rem Koolhaas had designed four library projects since the first competition entry for $Tr\grave{e}s$ Grande $Biblioth\grave{e}que$ in 1989. The purpose of this study is to analyze design process of spatial organization in the library projects by OMA in order to find out what similarities and differences are in design concept and how it evolved from the previous one. Seattle Central Library completed in 2004 has been known as new generation of public library in information era. Looking at that how the concepts of the four other libraries were used in Seattle library is the interesting subject and main contents of this study. In conclusion, Inventing new strategy to create the public space is the important concept which influenced the shape of the buildings, and also space density is the key theme which was applied to most public library projects in order to create public space.