A layered gradient material which comprises a plurality of layers composed of a mixture of hydroxyapatite and calcium tertiary phosphate and is obtained by producing a layered body by stacking a plurality of layers in which the compounding ratio of hydroxyapatite to calcium tertiary phosphate is stepwise or continuously changed and then sintering the layered body by the spark plasma sintering method is excellent in mechanical strength such as compressive strength, flexural strength and Young's modulus, and further, is excellent in biological reactivity such that in the case where it is used as a bone substitute material, bone destruction and new bone reconstruction actively occur. Accordingly, it is extremely useful as a biological material such as a bone substitute material, artificial tooth root and dental cement.