We developed a system that can detect the glass wall for mobile robot using 3D point cloud by 3D-LIDAR. When the robot moves around a human living space such as an office or a home with glass wall and glass window, we need the glass detecting system. Glass has the property of transmitting light, but when laser is vertically applied, it is reflected by specular reflection and glass can be detected. The intensity of point cloud from received light is high at the center area. The intensity of point cloud at surrounding area is very low. This system used pattern matching of the point cloud of glass wall for detecting the glass wall.