It was reported that the cationic ions are related to the adhesion behavior of integrin. Especially divalent cations such as Mg²⁺ ions play some role in cell adhesion. Thus, magnesium seems to be an important factor in controlling bone metabolism. Re-cently, scaffold biomaterials have been focused in the tissue engineering field. FGMgCO₃Ap-collagen composite was made by mixing the functionally graded CO₃apatite containing Mg with collagen. Modification of gradational Mg²⁺ ions on the apatite crystals promoted cell adhesion. Furthermore, as a scaffold material, the FGMgCO₃Ap-collagen composite suggested contributing to bone formation. Mg²⁺ ions may contribute to the bone metabolism of osteoclast and osteoblast action with the integrins at their cell surfaces.