The exclusionary rule is a judge-made doctrine that prohibits introduction of evidence obtained in violation of a defendant's Fourth, Fifth, and Sixth Amendment to the US Constitution. The Fourth Amendment to the US Constitution provides: The right of the people to be secure in their persons, houses, papers, and effects, against unreasonable searches and seizures, shall not be violated, and no warrants shall issue, but upon probable cause, supported by oath or affirmation, and particularly describing the place to be searched, and the persons or things to be seized. The exclusionary rule enforces this constitutional provision by excluding from the trial of a case any evidence that has been obtained by the government through means which violate the Fourth Amendment. The exclusionary rule operates as a bar to the use of evidence obtained as a result of an illegal search or seizure. The US courts have been reluctant to impose exclusion as a judicial remedy for a violation of a federal statute or regulation, or a Federal Rules of Criminal Procedure. The other major civilized country, such as UK, Canada, Japan, France, Italy, and Germany, also have their own exclusionary rule related with the improperly, illegally or unconstitutionally obtained evidence. The revised Code of Korean Criminal Procedure introduced the exclusionary rule of the US to the criminal justice system where Korean Supreme Court has been refusing to apply the rule to the material evidence which is obtained by the illegal search or seizure of the government. It provides that the evidence which is obtained by violating due process of law shall not be admitted. The admission of the evidence, in Korea, depends on whether the government followed the due process of law while the evidence that has been secured by violation of the constitutional right shall be excluded in US. In addition, the major opinion of Korean Supreme Court recently held that, in principle, the exclusionary rule should be applied to the material evidence if the evidence was obtained by the search or seizure process which did not follow the Korean Constitutional Law and Criminal Procedure Law. According to this ruling, there is a chance that the slight violation of the Criminal Procedure Code by investigative agents would result in exclusion. I disagree with this opinion of Korean Supreme Court because this opinion did not deeply considered the one of the goals in criminal procedure - the discovery of the truth. The standard of the exclusionary rule must be whether the illegality of government's violation is substantial or serious considering the spirit of due process of law. It was the minor opinion of that Supreme Court's ruling.