This study began from the idea that new materials and awareness in the modern society demand new methods in architecture and focused on diagrams as the tool many modern architects use in their process of architectural design. Therefore, the purpose is re-finding the potential of diagrams as profilerating architectural design media by examining mentions of architects about diagrams, investigating diagrams used in design process and treating comments referring to diagrams, by redefining the meaning of the contemporary architecture and of diagrams in architecture, and by grasping the various methods of use and its process. The design process using diagrams produces synthetic or reasonable process dissimilar to previous processes. Where diagrams are mainly used as tools to relate the segregated parts compressively. On the other hand reasonable process concerns reasonable design advancement to satisfy various requirements or conditions in reality, where diagrams are used as tools offering its phase in the whole structure of various information and relating steps of design each other. Dealing synthetically in the various steps of design process with the various properties originally obtained, proposing a new type of architecture by increasing thoughts and leaving the design process open-fluid, offering process and results having the same value as design process, and satisfying requirements in reality most reasonably, diagrams working in the above-mentioned design process have the potential to narrow the schism among theory, practice and criticism in contemporary architecture.