This paper deals with the newly developed ‘O-jiro (Onelegged ,jigging robot)’ which realizes stilts-walking. The impact of stepping by two legs disturbs the balance of the body, so this robot has a vertical arc-shaped plate for its leg. A single motor swings the leg cyclically, so the supporting point moves from side to side like steps of stilts-walking. At the same time, another motor drives a rotor mounted on the top of the body to turn the lifted leg toward the direction in which the body leans (forward or backward), so the O jiro can remain stable. He can thus realize stable stilts-walking, with a simple mechanism and only two actuators. As a results of experiments, it has been confirmed that he can remain stable standing and that this mechanism is useful as a locomotive robot.