Thanks to the developments of IT technologies, such critical infrastructures as fundamental structures of energies, material circulations, monetary circulations, and living necessaries are intertwined as well as mutually dependent. In this respect, the fact that national infrastructures are closely related to IT infrastructures implies not only expected benefits to provide diverse information-based services, but also anticipated costs to bring about new dangers. However, in spite of these threats, traditional researchers have not put enough interests in these indirect dangers, which yield the damages in broad areas through paralyzing risk management systems, although they have investigated such direct threats as nuclear accidents, conflagrations, traffic troubles, and gasoline accidents. Considering that the tendency to depend on electricity, so-called electrification, which is caused by automation and informationalization, is intensified in all parts of society, the breakout problem as a factor to inhibit securities in information-oriented society is significant. Thus, the problems of large-scale power blackout should be treated as national crises. Also, preparation systems for large-scale power blackout have to be provided quickly. In this paper, with analyzing various cases of large-scale power blackout and investigating the causes of them, researches on the blackout management systems of Korea are to be present, on the basis of national crisis management stages which are comprised of protection (mitigating and preparing), responding, and recovering (rewarding).