In correctional institution, Correctional officer through the special judicial police officer system perform investigation duties. This is to prevent a judicial vacuum by allowing them to conduct their own investigations because the general police force cannot reach them due to the specificity of the location control and operation of the correctional institution. However, the reality is that the military prison, which is a military correctional institution, cannot introduce a special judicial police officer system because military prisons are not included in the scope of prisons in the Judicial Police Officer Duties Act. The military legal system distinguishes between military status and civilian status due to the jurisdiction of status, and military investigation agencies cannot investigate civilians except for specific crimes. Nevertheless, inmates with military status and civilian status are detained together in the Military Prison, and when a criminal case occurs between inmates within the correctional institution, the civilian status inmates are investigated by the nearby civilian police, and the military status inmates is investigated by the nearby military police. There is a problem of inefficient case proceeding. Therefore, it is necessary to discuss the necessity and alternatives of the introduction of a special judicial police officer system so that inmates who are incarcerated in the military prison can be investigated regardless of their status.