An artificial joint apparatus used as an artificial joint inserted into a bone is provided. The artificial joint apparatus includes: a body having a stem having a shape substantially corresponding to a space within the bone, into which the stem is inserted, and a head formed integrally with the stem; and a jacket made of a plastic material and surrounding an outer surface of the stem of the body. The jacket is constructed with an outer layer containing a bone-friendly material and an inner layer mainly made of a plastic material. Since the plastic jacket of an artificial joint apparatus has a bone-friendly material, it is possible to promote a growth of a bone contacted thereto. In addition, the bone is grown into a space where the bone-friendly material is dissolved, so that the jacket and the bone can be securely adhered. Since the bone-friendly material also exists in an inner portion of the jacket it is possible to continuously accelerate a bone in-growth.