PROBLEM TO BE SOLVED: To provide a joint mechanism capable of suppressing discomfort felt by a user in exercise.SOLUTION: The knee joint mechanism of a movement assist device includes: a first slide member 33 connected to a thigh link 21 side and having a first slide track 33b formed into an arc shape projecting in an extension side； an intermediate slide member 40 that includes a first correspondence slide track 41b coacting with the first slide track 33b, and a second slide track 42c formed into an arc shape projecting in the extension side, and that is slidably connected to the first slide member 33 along the first slide track 33b； and a second slide member 37 that includes a second correspondence slide track 37b coacting with the second slide track 42c, that is slidably connected to the intermediate slide member 40 along the second slide track 42c, and that is connected to a lower thigh link 22 side, where the first slide track 33b and the second slide track 42c have different centers (C1 and C2) of curvature.SELECTED DRAWING: Figure 6【課題】運動時に使用者が覚える違和感を抑制できる関節機構を提供する。【解決手段】大腿リンク２１側に連結された、伸展側に凸の円弧状をなす第１スライド軌道３３ｂを備えた第１スライド部材３３と、第１スライド軌道３３ｂと協働する第１対応スライド軌道４１ｂ及び、伸展側に凸の円弧状をなす第２スライド軌道４２ｃを備え、第１スライド軌道３３ｂに沿って第１スライド部材３３にスライド可能に連結された中間スライド部材４０と、第２スライド軌道４２ｃと協働する第２対応スライド軌道３７ｂを備え、第２スライド軌道４２ｃに沿って中間スライド部材４０にスライド可能に連結されると共に下腿リンク２２側に連結された第２スライド部材３７とを有し、第１スライド軌道３３ｂ及び第２スライド軌道４２ｃが異なる曲率中心（Ｃ１、Ｃ２）を有する。【選択図】図６
