The basic structure of a wire suspended robot which ’walks’ along an aerial wire is proposed. The design and mechanism of robot legs to walk on a wire using linkage mechanisms is described. A slider-crank mechanism is analysed kinematically and applied to the robot legs. The robot has a gait achieved with the optimum design of the linkage mechanism which enables it simultaneously to avoid obstacles and travel stably. A walking robot was originally designed and constructed according to the evaluation of mobile stability. Experiments were carried out with the designed robot to clarify that the proposed method actually produces a stable walking motion.