In the highly motorized countries like Japan, the number of convicts who are sentenced to imprisonment for traffic accident offenses is increasing. Generally, these individuals are so different in character from other prisoners that it is undesirable to put them under strong restriction. Therefore, the Correction Bureau of Japan is trying to expand its open prison system and favors this type of facility for such offenders. The first open prison was introduced in 1961. Arii Branch Prison, established in 1968, is the only open prison in Chugoku District for traffic accident convicts. The typical traffic accident offender has no experience with other correctional institutions, is sentenced to a short term of imprisonment, has favorable conditions for returning to society, and is not physically or mentally defective. Regarding occupations, approximately 25 percent of those sentenced are professionals. Half of those sentenced are unmarried, and most are under 25 years of age. More than 65 percent of these individuals caused the death of one or more persons as a result of the traffic accident. The fundamental principle of treatment in Arii Open Prison is to facilitate the individual's return to society. Behavior is disciplined, but reading and similar leisure activities are rarely restricted. Visits and correspondence are encouraged to keep family ties strong. Convicts are persuaded to pay victims compensation whenever possible. Employment information is provided upon request. Convicts work with ordinary workers in common factories under contract during the term of imprisonment. The number of released prisoners totals 600 since the facility opened in 1968. Prisoners released on parole number 584, and 16 were released upon term expiration. The number of recidivists is 15. Tables are included.