Although one party to the contract fulfills its obligation to pay, the performance may result in a benefit to a third person who is not the other party to the contract. At that time, there is the right of the contracting party who has not received the payment, to claim the return of unjust enrichment against the third person. This is the right to claim the return of benefits transferred to others and it was called “actio de in rem verso” in Roman law. Sons or slaves whose rights were not recognized could enter into contracts and the head of household or the owner to take the profit transferred through that contract. At this time, the other party was entitled to claim the performance in accordance contract against the head of household or owner. Later, son's capacity for rights was recognized and slavery became meaningless. In the era of common law, the relative effect of contracts began to be recognized as a general principle of civil law. Then, the “actio de in rem verso” were no longer dealt with under contract, but in terms of claims for unjust enrichment and return. Currently in Germany, France, Japan, and Korea, this is also discussed as part of the claim for the return of unjust enrichment. Our Supreme Court completely denied the “actio de in rem verso” in 2002. This is because it is contrary to the basic principle of contract law. The loser passes the risk of the contract to the beneficiary. This makes the loser superior to the general creditors of the intermediary. This violates the right of defense that the beneficiary can assert against the intermediary. The Supreme Court has denied the “actio de in rem verso” on this ground. However, as we have seen earlier, “actio de in rem verso” only have the nature of the right to claim unjust enrichment and return since common law. It is no longer a contractual right. The recognition of this right shall then depend on whether it has met the requirements for establishing the right to claim for unjust enrichment. Nevertheless, it is questionable that our theories and precedents to deny “actio de in rem verso” because this right is not in accordance with the principles of contract law. I think it is necessary to review “actio de in rem verso” positively if considering the theoretical aspect of the law in order to solve the legal relationship in Korean civil law. Article 747 (2) of the Korean Civil Code provides that the first loser has the right to claim for unjust enrichment against the beneficiary who knows that there is no legal cause and acquires a benefit of a free from intermediary. Regardless of their legislative intent, this provision represents a typical “actio de in rem verso” between persons who are not parties to a contract. Furthermore, it cannot be denied that the Supreme Court has issued a number of positive rulings on “actio de in rem verso” after the 2002 ruling which denies.