Penal institutions denote prisons, juvenile prisons, and detention houses. Prisons and juvenile prisons are institutions whose principal role is to house offenders sentenced to imprisonment with or without labor, or penal detention for the execution of their sentences and provide necessary treatment for these offenders. Detention houses are institutions that mainly house inmates awaiting trial (defendants and suspects in custody; hereinafter the same). Penal institutions have workhouses in which offenders who are unable to pay fines or minor fines are detained, and also have houses of Kanchi confinement in which persons subject to non-criminal confinement as the punishment for contempt of court (Kanchi confinement) under the provision of Article 2 of the Law for Maintaining Order in Courts, etc. are detained, except for some penal institutions.
  As of April 1, 2002, there were 74 penal institutions (59 prisons, 8 juvenile prisons and 7 detention houses) and 115 branch institutions (5 branch prisons and 110 branch detention houses).
  As of December 31, 2001, the imprisonment capacity of penal institutions was 64,727 inmates (including 48,911 convicted inmates), while the actual number of imprisoned inmates was 65,508 (including 53,647 convicted inmates). Fig. 2-4-1-1 shows the trends in the rate of imprisonment since 1982. As of December 31, 2001, the rate of imprisonment (the rate of actual inmates to the imprisonment capacity) was 101.2% for all inmates (up by 5.8 points from the previous year) and 109.7% for convicted inmates (up by 6.1 points), which indicates that about 80% of penal institutions housed inmates beyond their capacity (Source: Correction Bureau, Ministry of Justice). Staff who work at penal institutions are prison officers (officials in the Ministry of Justice with custodial authority under the Prison Law) as well as technical and education officers in the Ministry of Justice.

Fig. 2-4-1-1 Trends in the rate of imprisonment of penal institutions (As of December 31 in 1982-December 31, 2001)