Crickets display escape behavior when they encounter against sudden intense mechanical stimuli to the tip of hind wing. They usually change their step pattern during escape. We can analysis details of such unique leg moving pattern with the technique that based on robotic research. This analysis revealed that the surprised animal must make immediate forward moving by sudden exension of hind leg tibiae even when the legs are in different step phase. In such case, animal steer their body to foward direction with their fore legs.