The main role of the Juvenile Vocational training center is to rehabilitate young offenders and support their social reintegration, including protecting communities from unsafe situations. Imprison offenders would be faced a real challenge at the time of their release unless efficient and effective programs are provided. The paper analyzed the cost per unit and examined the Economies of Scale of the 17 juvenile vocational training centers across Thailand. The analysis was based on a data set during 2016 - 2019 from the Department of Juvenile Observation and Protection. The average cost per unit in the center was $168 per month or $2,018 annually. The results revealed that both small- and large-scale centers were inefficient. Incidentally, this cost per unit paid for an offender was lower than the national comparing average cost of living. Therefore, the means of increasing operational efficiency in Juvenile Vocational Training Center must be exerted to avoid the internal diseconomies of scale.