Recently, the Organized Crime has a tendence in increasing and its method of crime is diverse and intelligent by means of lawful business and company, disguising the lawful, including unlawful method. Because of the circumstances above-mentioned, it needs to introduce restrictively the system of Undercover Employees as a means of investigation, to protect and repress effectively the organized crimes. The Undercover Investigations have some merits which can allow to know the whole things, only a member of organized crime can know, and which can protect and treat effectively the crimes and by means of collecting the all information about the crime in effectiveness of crime investigation. Though Undercover Investigation is an effective investigation method in investigating the organized crimes, there must be some worries of its abuses, because Undercover Investigation is executed by the Government and does not have any regulation and rule. Ordinarily, general investigation is open and has a characteristic of posterior measure. On the other hand, Undercover Investigation is disguised, fraud and used by the attraction method and has a characteristic of proactive and confidential measure. Because of the confidential method of Undercover Investigation, it is not easy to collect the information about Undercover Employees. So, it is compulsory that Undercover Employees should be run by the Court`s Admission or Warrant of Undercover Investigation, because there must be the violations of Human Rights. In some needs of protection of undercover employees, we can have some problems in Prosecution Process. It is not possible to take the undercover employees as a witness and it can crashed by the party`s interrogation of witness. And there can be more problems like qualification of evidence, crimes of Undercover Employees and so on. It should be prudent to introduce and adopt the Undercover Investigation or Undercover Employees, because there are some problems that the essence of Undercover Investigation can not divided crime world and non-crime world, and crime investigation`s superiority to ethics, destruction of citizen reliability. In some reasons above-mentioned, Undercover Employees should be introduced restrictedly by the consideration of benefits of investigation and guarantee of civil rights, benefits of governments by means of comparative weight.