Recent DDoS attacks and private informations leaked show that everyday life is interwoven with cyberspace and we are becoming more vulnerable to cyber attacks. Therefore, a systematic understanding of cyber damage structure is very important and damage loss estimation method should be developed to establish solid cyber security protection system. In this study, economic loss caused by cyber attacks are surveyed based on the analysis of existing studies and try to develop a reasonable methods to estimate economic effects of cyber security protection in Korea. Potential economic loss of Korea by cyber attacks may be situated between 10 billion and 40 billion dollars. But more sophisticated system should be established to estimate economic effects of cyber protection for proper policy decision making.