A magnesium alloy of the present invention has a structure, comprising: 0.5-2.0 wt % of Zn; 0.3-0.8 wt % of Ca; at least 0.2 wt % of Zr; and the remainder comprising Mg and unavoidable impurities, wherein a nanometer-sized precipitate comprising Mg, Ca and Zn dispersed on the (0001) plane of a magnesium matrix, thereby achieving both formability and strength in a range of temperatures including room temperature.