We aim to make a one-legged hopping robot hop continually by remote control, and finally to gain stabile balance control employing a neural network-based controller. Because it's essential to balance the robot by remote control so the hopping time is improved, we develop a robot with an active-suspension mechanism composed of a spring and DC motors. We need motors with high revolution rates and torque, and we haven't been able to gain enough the hopping time because of the motor's performance limitations. In this study, we have designed and built new robot employing clutches with hemispherical teeth, and evaluated the hopping experiments. As a result, we found that it was possible to have the clutch attach and detach smoothly and quickly, and that the hopping time can be improved by the clutch mechanism. Moreover, we found that the continual hopping was affected by the timing of detaching the clutch.