To provide a biocompatible Mg alloy which can be applied to the material for medical use and further can be applied to the material for dental use.

The biocompatible Mg alloy contains, by weight, about 15 to 80% aluminum (Al), about 7 to 40% yttrium (Y), and about 10 to 70% magnesium (Mg). As the material for dental use, an Mg alloy suitable for the living body containing about 45 to 80% aluminum, about 7 to 40% yttrium and about 10 to 40% magnesium is preferable.