An object of the present invention is to suppress flexion of a knee when the limb is standing with the knee fully extended. A load support tool 2a for supporting a load and a thigh of one leg of a user are mounted, one end portion is swingably connected to the load support tool 2a, and a thigh engagement portion 3a is connected to the other end portion. The long thigh link 2b1 having the long thigh link 2b2 whose one end is rotatably connected to the other end described above and the thigh link 2b2 are arranged at one end, and the thigh engaging portion is one end. An engaging member 3b having a crus engaging portion 3b1 that can engage with 3a, and a grounding sensor 3b3 that detects grounding, and when the grounding sensor 3b3 detects grounding, the user's knee is extended. In this case, when the thigh engaging portion 3a and the crus engaging portion 3b1 are engaged to stop the relative rotation of the thigh link 2b1 and the crus link 2b2, and the user's knee is not extended, the thigh engaging portion 3a and the crus The joint portion 3b1 was not engaged. [Selection] Figure 1【課題】膝が完全に伸展した状態で立脚しているときの膝の屈曲を抑制すること。【解決手段】荷重を支持する荷重支持具２ａと、ユーザの一方の脚の大腿に装着され、一端部が荷重支持具２ａに揺動可能に連結され、他端部に大腿係合部３ａを有する長尺状の大腿リンク２ｂ１と、一端部が、前述した他端部に回動可能に連結される長尺状の下腿リンク２ｂ２と、下腿リンク２ｂ２に配置され、一端部が大腿係合部３ａと係合可能な下腿係合部３ｂ１を有する係合部材３ｂと、接地を検出する接地センサ３ｂ３と、を備え、接地センサ３ｂ３が接地を検出したときに、ユーザの膝が伸展している場合、大腿係合部３ａと下腿係合部３ｂ１が係合して大腿リンク２ｂ１と下腿リンク２ｂ２の相対回動を止め、ユーザの膝が伸展していない場合、大腿係合部３ａと下腿係合部３ｂ１が係合しないようにした。【選択図】図１
