In this paper, we develop tw o mechanisms for improving humanoid robot motions. The double spherical joint is a six DOF mechanism whose axes intersect in one point. This mechanism is for humanoid hip joints with a waist join t function without increasing an actuator.The backlash clutc h realizes a high torque driving and a really free join tusing backlash mechanism, and it is used for knee joints. The free mode will play a roll in humanoid behavior that is dynamically coupled with the environment. The humanoid robot with these t w o mechanisms is developed and results of preliminary experiments are to be shown.