Autonomous navigation of an indoor mobile robot, using the global ultrasonic system, is presented in this paper. Since the trajectory error of the dead-reckoning navigation increases significantly with time and distance, the autonomous navigation system of a mobile robot requires self-localization capa-bility in order to compensate for trajectory error. The global ultrasonic system, consisting of four ultrasonic generators fixed at a priori known positions in the work space and two receivers mounted on the mobile robot, has a similar structure to the well-known satellite GPS(Global Positioning System), which is used for the localization of ground vehicles. The EKF (Extended Kalman Filter) algorithm is utilized for self-localization and autonomous navigation, based on the self-localization algorithm is verified by experiments performed in this study. Since the self-localization algorithm is efficient and fast, it is appropriate for an embedded controller of a mobile robot.