A lower-limb joint orthosis includes a lower component supporting the foot region, an upper component attached to the lower-limb, and an orthotic joint coupling both components. The orthotic joint comprises: a stator including some fluid chambers in which an MR fluid is enclosed and a rotor including partition plates protruding into the respective fluid chambers. The stator includes a communication path between the anterior chamber and the posterior chamber. The rotor includes connection paths that connect the anterior chambers together, and connect the posterior chambers together. An electromagnet is placed on a side surface of the communication path so that a rotational resistance of the lower component and the upper component is adjusted by adjusting a magnetic force to control the viscosity of the MR fluid that flows through the communication path.
