Recently, mobile robots have been researched to solve the labor shortage. Environmental measurement by 2D LiDAR (URG) mounted on a mobile robot is indispensable for autonomous movement of the robot. There is a problem that the slope is misidentified as a wall and a ghost problem that unintended data is obtained when the environment measurement by URG is performed. The slope problem utilizes the fact that the angle of incidence changes depending on the inclination, and shows that there is a difference in intensity between the wall and the slope. For the ghost problem, we show that the change in distance has a behavior similar to the tanh function.