To improve functionality of a joint orthosis arthrosis.

The joint orthosis is provided with an upper arm 32 and a lower arm 33 each arranged at both sides of a joint orthosis, which are joined by a fulcrum shaft 34, 35 in free turning, and is provided with a stopper so that they halt at full extension no to go and bend toward an opposite side. A coupling part of the upper arm and the lower arm of one side and that of the other side are coupled with a coupling member 40 so as to surround the joint part. The upper arm 32 and the coupling part 31 or the lower arm 33 are fitted with fixing belt 41 for holding down an upper part of the joint orthosis.