保安处分是以社会防卫为目的、替代或者补充刑罚而适用的刑事制裁措施。保安处分的产生和发展有其经济、科学和社会的深刻背景,以新派教育刑的行为者理论、社会责任论和社会防卫论为理论基础。关于保安处分的法的性质有一元论与二元论之争。一元论认为应该由保安处分替代刑罚而适用,最终统一于保安处分。而二元论则认为保安处分与刑罚是两种不同的措施,在性质上应加以区别。纵观世界各国的理论和立法实践,二元论更为可取。 Security measures are criminal sanctions that are applicable to social defense instead of or in addition to penalties. The birth and development of security measures have profound economic, scientific and social backgrounds and are based on the theoretical basis of the new educational theory of criminal actors, social responsibility theory and social defense theory. The nature of the law on security measures includes monism and dualism. Monism holds that security penalties should be replaced by criminal sanctions, and finally unified in security measures. However, dualism considers security measures and penalties as two different measures, which should be distinguished in nature. To sum up the theories and legislative practices of all countries in the world, dualism is preferable.