To enable a highly strong and rigid stem to be used even though it has small diameter, by forming a sliding face spherical, equipping a tapered hole to be fit by a stem, and forming a ring shaped reinforcing protruding part so as to be protruded outside along the periphery of the tapered hole opening part.

A metallic stem 4 of an artificial articulation is formed into a long shape tapered to the end part side which does not fit with a ceramic caput ball 3 and is fixed via a bone cement into a hole part formed by bone- cutting at the proximal end of a thigh bone. An artificial socket is formed spherical inside and is fixed via a bone cement onto a dent part formed by bone cutting at a socket. A spherical sliding face 10 is equipped on the ceramic caput ball 3, a tapered hole 11 opened toward the surface opposite to the tip end of the sliding face 10 is formed in the radial direction of the sphere formed by the sliding face 10, and the tip end of the stem 4 is fit into the papered hole 11. A reinforcing protruding part 12 is formed so as to protrude outward onto the opening part periphery of the tapered hole 11.