This study summarized the concept of cyberspace systemically, and presented the development structure of cyberspace through discussing 1) how replace existing physical space with cyberspace and interact with them 2) what is optimal linkage structure between cyber space and physical space.To diagnose the possibility and actuality of digitalization in empirical aspect, I implemented survey research about possibility of digitalization of government functions. This study introduced digital index (DI) for measuring the possibility of digitalization of government functions. Digital Index (DI) is composed of four sub indexes: possibility of digitalization, economic efficiency, dependency on other factors, and requirement of physical functions. With the introduction of digital Index, the most important 16 government functions were evaluated to determine to what extent those functions could be digitalized. Possibility of digitalization was used here to indicate the extent to which government functions and services can be processed and provided on the internet, cyber space. Based on the evaluation results, all government functions were classified into three different groups. First types of government functions are those with high possibility of digitalization and low necessity of linking those functions to physical space. This type of government functions can be well implemented and provided in the cyber space alone. Second types of government functions are those with high possibility of digitalization and high necessity of linking those functions to physical space. This type of government functions need to be implemented and provided both on the physical space and cyber space as well at the same time. These functions need to be implemented both on the cyber and physical space at the same time to be most efficiently implemented. The third types of government functions are those that can be implemented more efficiently on the physical space rather than on the cyber space. These functions are most efficiently and effectively implemented in the physical space rather than cyber space. Thus, digitalization of government functions need to be proceeded in accordance with these classification of government function to get the most out of the government digitalization project. This study addressed positive effect and ability of linkage space, not divided space, as well as scheme overcoming the functional limits of physical space and cyberspace by rearranging key functions of government at both space.