Roughened surface was formed on the surface of Co-Cr-Mo-W alloy substrate by applying doubled sandblasting method using silicon carbide grinding particles with 14 μm and subsequently 8 μm in average diameter. In order to impart hydroxyapatite formation ability to the Co-Cr-Mo-W alloy, the substrate was immersed in simulated body fluid (SBF) with ion concentrations nearly equal to those of human blood plasma adjusted at higher pH in comparison with those of physiological SBF and heated. By this treatment, apatite nuclei were formed on the Co-Cr-Mo-W alloy. By immersion in physiological SBF, hydroxyapatite covered whole surface of the substrate within 3 days and high hydroxyapatite formation ability was performed. The formed hydroxyapatite layer was adhered by mechanical interlocking effect between the substrate with roughened surface and the hydroxyapatite layer.