Recently, in the various international negotiations and discussions, the necessity has been stressed to evaluate, introduce and implement Confidence-building Measures. Such measures are effective steps aiming to strengthen the international security and to facilitate disarmament negotiations among States, by reducing or eliminating the cause for mistrust, fear, tensions and hostilities as significant factors behind the international arms build-up and conflicts, and, accordingly, by establishing the trust among States. In 1981, Report of the Secretary-General, 'Comprehensive Study on Confidence-building Measures' was elaborated by the Group of Governmental Experts on Confidence-building Measures, and was submitted to the General Assembly. In this paper, the present writer will examine the international instruments related to the preparation of this Report, including the Final Act of the Confidence and Security and Co-operation in Europe, and the Final Document of the Tenth Special Session of the United Nations General Assembly devoted to disarmament, and then will clarify that such measures are useful to improve the international relations by introducing and analysing the content of this Report.