Imprisonment plays and stands the important roles to substitute the pre-modern corporal punishment to the modern punishment systems. The main purpose of imprisonment execution is rehabilitation for convicts by preservation of public peace and reformation education. However, it is not convinced that the current imprisonment system as "ideal punishment" with execution purpose of convicts' rehabilitation has performed satisfactorily. Therefore, reconsideration for restriction of freedom itself should be reflected and an alternative punishment institution for imprisonment shall be searched and studied. From this point of view, it seems criminal policy should head forward to the direction that can control the restriction of freedom as much as possible. This dissertation, hence, reviews the "Materialization and Features of Modern Imprisonment Systems" and examines "Limitations and Controversial Issues of Imprisonment as Criminal Policy". And then, to present the development schemes of Korean execution system, "Successive Adaptation Plans for Limitation of Freedom", "Expansion of Parole System and Application of Probation System" and "Establishment of Correction Agency" are studied. "Successive Adaptation Plans for Limitation of Freedom" exhibits the supervision treatment and open treatment programs; in "Expansion of Parole System and Application of Probation System" section, necessity of close connection between parole and probation systems is emphasized; and "Establishment of Correction Agency" reconsiders the efficiency of reformation administration and asserts the establishment for supervision office to inspire public service personnels morale. In conclusion, to draw out the goals of current criminal policy as it is, imprisonment execution system is inevitable. Nevertheless, pains from restriction of freedom must be mineralized, that is, the system should be the one minimizes the reactions or side effects from isolation from society and personal imprisonment. To do this, from humanitarian, rational and economic points of view, open-reformatory, practical programs of releasing before the expiration of terms and alleviation of unessential regulations are demanded. Steady contacts with society and extension of association scope will relax convicts affliction caused by separation from society and be easy to rehabilitate, accordingly, Korean criminal policy should head forward to the system that emphasizes treatment within society.