Severe criminals are often long-term prisoners and they experience difficulty returning to society or psychological anxiety while being in the service, as well as there is a high possibility of correctional accidents or recidivism among them. it is necessary to specialize and diversify the treatment for severe criminals in both facilities and society. However, there is no definition of several criminals under the current law and there is also no effective and suitable treatment for them. The correctional ideology we need to pursue is to treat individual inmates in consideration of the personal characteristics of each prisoner. As an aspect of current correctional practices, serious offenders are defined as “a prisoner in a high overall level of security” and “a high-risk prisoner”, however, the individual treatment principles have never been feasible under the system. Correctional facilities to accommodate and manage them exclusively are also insufficient. To overcome this problem, we should establish a unified standard for severe criminals as sentenced to a long-term sentence for a crime against a person's life or body. In addition, a systematic management should be established considering the distinctive characteristics of a long-term prisoner. Sustainable individual treatment plans for the severe criminals should be introduced by improving facilities and expanding them dedicated entirely to severe criminals as well as utilizing re-risk assessment.