A knee brace capable of correction only in a required angle range and of reproducing a normal screw-home movement in a knee joint of a knee osteoarthritis patient having outer and inner leg joints including first and second couplings coupled at coupling portions. The coupling portion includes a cam groove, a long groove, a rotation fulcrum shaft, and a cam shaft. When flexing the knee, the rotation fulcrum shaft and the cam shaft slide in the long groove and the cam groove and the second coupling rotates around the coupling portion with respect to the first coupling to flex the leg joints, and when extending the leg joints, the rotation fulcrum shaft and the cam shaft slide in the long groove and the cam groove to move the second coupling on the outer leg side upward and rearward and the second coupling on the inner leg side downward and forward.
