Today each country in the world goes beyond the narrow concept of national security that was limited to national defense and ideology and are entering multi-dimensional global system mainly based on economic profits. Nevertheless, conflicts between nations due to religious and ideological reasons have brought unprecedentedly intense disputes Security services for head of states have been an important national mission in every era and society. However, they are becoming a main target for assassination and attacks by terrorists. Attacks on the head of state and other VIPs can cause aftermath ranging from war to conflict situation, political crisis, and economic loss. Therefore this study aims to draw insights by comparing protective security units of Korea, the U.S., and Japan which have different legal basis and sociocultural characteristics. Especially in South Korea, which faces difficult diplomatic stance due to the tension with North Korea and relationship with other countries such as the U.S., China, and Russia as well as polarization between classes, generations, regions, and ideologies, cohesion among members of society has weakened and hatred toward the head of state has been brought, which emphasizes the important of national security services. Therefore the study of protective security units and its operation by comparison between neighboring countries will be able to bring insights on the promotion of the security service.