PROBLEM TO BE SOLVED: To provide a component for joint prostheses capable of reducing a risk of damage by providing a structure difficult to cause damage and improving a fixing property for obtaining fixing force with respect to a bone.SOLUTION: An inner structure 13 includes at least an inner section as a recessed surface 11 in a body part 12, to which a liner in which a ball-like component 4 slides is attached. An outer structure 16 is provided outside the inner structure 13. The inner structure 13 is configured as a dense body, while the outer structure 16 has a porous section 18 configured as a porous body as a structure looser than the dense body of the inner structure 13. The inner structure 13 and the outer structure 16 are integrally molded.
