Magnesium alloy

Patent Granted PROBLEM TO BE SOLVED: To provide a high-strength magnesium alloy having improved high-temperature strength while its cost is made low without using expensive rare earth elements, and to provide its production method. ; SOLUTION: The high-strength magnesium alloy is expressed by the compositional formula of Mg<SB>100-(a+b)</SB>Zn<SB>a</SB>X<SB>b</SB>, wherein, X denotes one or more selected from Zr, Ti and Hf, a and b are the contents of Zn and X expressed by at%, respectively, and satisfy the relations in (1)a/28<=b<=a/9, (2)2<a<10, and (3)0.05<b<1.0, and in which Mg-Zn-X quasi-crystals and crystals close to those are dispersed into an Mg mother phase in the form of fine grains.