In this paper, we propose an azimuth estimation method for mobile robots. In our method, artificial walls within the detection range of the LIDAR mounted on the robot are used for estimation of the azimuth angle. Each wall is approximated as a plane, and the normal vector of this is used for some processes. By means of this reasonable approximation, the surrounding environment is described with extremely little amount of data. This leads the real-time property of the method. Additionally, taking account of the kinematic performance of the robot, robustness and high-responsiveness is realized. At the end of this paper, the utility of our method is shown through two experiments.