Most of the public infrastructure equipment currently in use was built during the period of high economic miracle and is rapidly aging. On the other hand, the number of workers who inspect those infrastructure facilities has been decreasing in recent years. In particular, the inspection work of underground buried infrastructure requires a great deal of labor and time, so the introduction of autonomous mobile robots is required from the viewpoint of improving the efficiency of inspection work and saving labor. High self-position estimation accuracy is required to identify the position by comparing the coordinates of autonomous movement and underground buried objects with the information of the ground penetrating radar. In this study, we constructed a two-dimensional relative positioning accuracy evaluation experimental system assuming inspection of underground buried objects by an autonomous mobile robot, and conducted self-position estimation experiments using an axle encoder and self-position estimation experiments using sensor fusion.