The purpose of this research is to provide a comprehensive international legal analysis of the concept of common heritage of mankind as it exists in international space law. In this article scientific methodological approach was used which facilitate determination the whole canvas of the research, identify the main aspects and concepts of the study. The author also widely investigated the concept of common heritage of mankind in the practice of States and international organizations and bodies. Since mankind succeeded to access outer space and opened the window of this infinite realm, the effort was made to systematize spatial activities by codification and adoption numerous international treaties and declarations. One of the significant result of these efforts was the Agreement Governing the Activities of States on the Moon and Other Celestial Bodies that adopted by the United Nations Committee on the Peaceful Uses of Outer Space by consensus on 5 December 1979, declares the Moon and other celestial bodies to be the common heritage of mankind. This Agreement has never been ratified by any State that engaged in self-launched manned space exploration or has plans to do so and thus has an insignificant effect on spatial activities. This article analysis the concept of common heritage of mankind that consists of five elements: non-appropriation, international management of resources, sharing of financial and technological benefits, reservation for peaceful purposes and reservation for further generations. It is shown that the Moon Agreement applying the concept of common heritage of mankind to outer space, Moon and other celestial bodies which has been presented by developing countries to preserve essential resources, always been associated with some problems. Also, on the one hand, there is an attempt to scrutinize these obstacles that prevent applying this concept by paying attention to its challenges. On the other hand, author presents some solutions to strengthen this concept in outer space legal system and motivate space powers to join the Agreement Governing the Activities of States on the Moon and Other Celestial Bodies.