An artificial joint includes a ball and a cup constituting a pair of joint members which forms a joint. A convex curved surface and a concave curved surface which constitute a pair of friction surfaces which slides relative to each other are provided between the pair of joint members. The convex curved surface which is at least one friction surface out of the convex curved surface and the concave curved surface includes: at least either one of groove-shaped recessed portions and hole-shaped recessed portions having a width gradually narrowed toward the inside of the convex curved surface from a surface side of the convex curved surface and curved surface portions which smoothly connect inclined surface portions which form the recessed portions and a surface which forms a surface portion of the convex curved surface.
