Development of IT technology as well as arrival of information-oriented society raise the curtain of \"the era of Ubiquitous Computing\", implying accessing computers beyond boundary of time and space. In this era, it is expected that IT paradigms and life-styles would be transformed immensely above the experiences of 20th century. However, improvement of technology summons a new risk of cyber terrorism which have not been in the past. Thus, it is urgent to prepare for the threats in the national level.
This paper point out five major threats relating to \"the security in the era of Ubiquitous Computing\". : First, spread of threats in connection with BcN establishment, second, vulnerable information-security for wireless communication, third, leakage of private information, fourth, cyber terror and deterioration of security, fifth, security problems of Korea including the drain of military information and solutions in the views of organization, personnel, technology and budget, comparing with other countries.