The present invention relates to a biodegradable magnesium alloy comprising x wt% of calcium, y wt% of zinc, and the balance of magnesium and inevitable impurities, wherein x and y have a range corresponding to a region in which the lower part of the trajectory of mathematical formula 1 (y = 44.894x2 - 25.123x + 5.192) and the upper part of the trajectory of mathematical formula 2 (y = - 10.618x2 + 7.8784x + 0.1637) overlap in the x-y plane, and a zinc compound phase contains 90 wt% or more of Ca2Mg6Zn3 on the basis of the total weight of the zinc compound phase.
