Since last half of the 20th century, soft law has emerged from regulating newly faced international issues including human rights, environment, and trade. The concept of soft law has been broadly recognized today and will be much more utilized in future. Unfortunately, however, it has not established a unified concept. Commentators have used the term differently. Therefore this article seeks to make an outline of the concept, status and role of the soft law. This article examines the concept of soft law. Although the use of the term is diverged, there is common characteristic in its usage. Basically, documents classified as soft law don`t pertain to hard law, which is made up of the norms creating precise legal rights and obligations. Although they legally have no binding force, there are at least good faith commitments. Also, there are law-making will, parties` intension affecting state practices, and elements for progressive developments in many cases. As a consequence of legal implication, soft law documents have become alternatives to treaties, and complemented implementation of already concluded treaties, and have provided its own mechanism for soft enforcement. This interaction between hard law and soft law has made soft law documents with certain status in international legal system and some effect on international affairs, and, as de facto effect, has altered behaviors of their addressees. In conclusion, soft law documents are not a source of law in the sense of Article 38 para. 1 of the Statute of the International Court of Justice. Soft law should be regarded as a conceptual tool. Therefore, a further research on soft law should elaborate the normative value of non-binding instruments in detail and make a systemaitc analysis of these instruments.