Pure magnesium and its alloy, with elastic modulius (about 40 GPa) much closer to that of the natural bone, can enable to avoid the“stress shield”effect when implanted into human bodies as bone replacement materials. However, the low corrosion resistance of magnesium and its alloy, especially in body solutions containing Cl~-, has restricted its extensive application as bone implant materials. So, the surface protective methods are necessary to provide the control of corrosion rate. In this thesis, t...