The principle of “nulla poena sine lege” prohibits criminal law would be enacted retroactively. In the substantial viewpoint, it is a kind of criminal sanction whatever we call it punishment, security-measure or forced labor, etc, if the life, personal liberty, freedom, property or honor of citizens for a crime is restricted by governmental authority. Therefore, the order to make an offender committed specific crime wear a electronic ankle bracelet is a kind of criminal sanction. The governmental authority should adhere strictly to the prohibition of retroactive legislation that constitutes the principle of “nulla poena sine lege” when they exercise the government power to inflict a punishment. Nevertheless, the act on the electronic monitoring has been amended to impose the order to make wear a electronic ankle bracelet, the amendment is against the prohibition of retroactive legislation. The object of the modern criminal law is resocialization of criminals. Also, the act on the electronic monitoring is professedly for the purpose of resocialization in the article 1. To attain the aim to prevent sexual offenses and violent crimes from occurring, the social foundations for the criminals to return to life of a clean citizen should be secured. However, the electronic ankle bracelet actually disturbs the favorable social life and the formation of relationship with a person, and the person who is put on the electronic ankle bracelet committed suicide in the extreme case. The modern criminal law in concordance with the constitution prohibits the guilt-by-association system. According to the announcement of the Ministry of Justice, they have the plan to extend the scope of the crime to make wear the electronic ankle bracelet. To prevent sexual crimes from occurring, the Ministry of Justice has enforced the opening of personal information about sexual offenders by the homepage service of the Ministry of Gender Equality & Family and the notification of the information by post. All sorts of measures including the order to make wear the electronic device, the opening of personal information about sexual offenders and the notification by post have inconvenienced the family of the sexual offenders. In conclusion, there is grave concern that the electronic device bring about a contrary effect rather than a prevention of crime. It is necessary that the order to make wear the electronic ankle bracelet will be reconsidered.