As wear of the frictional material is suppressed, the living body activity by the worn powder which it occurs from friction surface is suppressed. The ball it possesses 20 which is the glenoid component of the pair which forms the joint and cup 30, between the glenoid component of these pairs, through lubricating liquid 40, the convex curved surface the artificial crotch joint 10 which forms 21 which is the friction surface of the pair sleeve relatively when it is contacted mutually and concave curved surface 31, convex curved surface the convex curved surface 21 which inside 21 and concave curved surface 31 at least is the friction surface of one side, from surface side of convex curved surface 21 betting on inside, at least each crevice forms 23 of grooved and the hole condition where gradually width becomes narrow and crevice 23The curved surface 24 which threads with the slant surface part 23a which it does and the surface which forms the surface of convex curved surface 21 smoothly and, it possesses. In addition, desirably, depth of crevice 23, being large, is submicron size.摩擦材料の摩耗を抑制するとともに、摩擦面から生じる摩耗粉による生体活性を抑制する。関節を構成する一対の関節部材であるボール20及びカップ30を有し、これら一対の関節部材間に、潤滑液40を介して互いに接触した状態で相対的に摺動する一対の摩擦面である凸曲面21および凹曲面31を形成する人工股関節10であって、凸曲面21および凹曲面31のうち少なくとも一方の摩擦面である凸曲面21は、凸曲面21の表面側から内側にかけて徐々に幅が狭くなる溝状および穴状の少なくともいずれかの凹部23と、凹部23を形成する斜面部23aと凸曲面21の表面部を形成する面とを滑らかに繋ぐ曲面部24と、を有する。また、好ましくは、凹部23の深さは、大きくてもサブミクロンサイズである。
