The purpose of this research is to develop a system which gives blind people information of the environment around them. A person is equipped with a 3D scanner and a small sized PC while walking. The scanner scans and acquires 3D range data map of the environment. The PC analizes the range data map and detects objects which are useful for blind people in orde to walk. The PC gives environmental information to them by synthesized sound. This paper first introduces the concept of the whole system and clarify the tasks for realizing the system. Secondly the method for acquisition of 3D range data and detecting objects and obstacles are described. Then the usefulness of our proposed system is examined by an experiment in which our trial system detects bumps and trenches in the experimental environment.