The present invention provides a knee joint that is energy efficient, small and lightweight, and capable of wide range of movement. The present invention also provides a knee joint that is active and relatively inexpensive. The drive unit 1 moves the driven member 21. The elastic member 22 is disposed between the driven member 21 and the linear motion member 23. The linear movement member 23 moves elastically in at least one direction through the elastic member 22 according to the movement of the driven member 21. The crank mechanism 3 can realize the bending or extending operation of the knee joint by converting the linear motion of the linear motion member 23 into a rotational motion.本発明は、エネルギー効率が良く、小型かつ軽量で、可動範囲を広くとることが可能な膝継手を提供するものである。また、本発明は、能動型でありながら比較的に安価な膝継手を提供するものである。駆動部１は、従動部材２１を移動させる。弾性部材２２は、従動部材２１と直動部材２３との間に配置される。直動部材２３は、弾性部材２２を介して、従動部材２１の移動に従って、少なくとも一方向に弾性的に移動する。クランク機構３は、直動部材２３の直線運動を回転運動に変換することによって、膝継手の屈曲又は進展動作を実現できる。
