Nowadays, Internet technology percolates our lives and it gradually changes the state of social life. Internet has a high degree of freedom to provide connectivity globally. Also, Internet is a global infrastructure designed to solve many kinds of problems by simply making good use of it. Internet improves the convenience of many things, however, security problems like leakage of information and illegal access has been manifested. Securing the internet is required for infrastructures, but it is a highly technical problem and it dynamically changes with time. Thus, in order to perco the Internet as a social infrastructure, expanding security measures is required. The security measure which conveys global viewpoints have to deal with problems that get elaborately entangled . While the security measure consists of two elements, technical and systematic elements, it is strongly related to government policy. It is also affected by policy enforcement or treaty. Also, you need to deal with transmutative risks when considering security management. In this situation, cyber crime has been dramatically changing recently. In addition to conventional cyber attacks, cyber terrorism is emerging against a background of political thoughts and high-tech crime is expanding to pursue economic benefits, which is taking advantage of the advanced use of information technology. In this lecture, we deal with security issues in the current Internet technology and explain countermeasures used in society and organization. In addition, technologies that could resolve problems and how to formulate rules will be discussed. Moreover, we assume the participants to consider what form of security measures should be from various viewpoints. This lecture is jointly delivered with faculty of Information Science, Graduate School of Nara Institute of Science and Technology.