The present invention relates to a desulfurizing agent of improved oxidation resistance, ignition resistance and productivity, and a method for manufacturing the desulfurizing agent. The desulfurizing agent may include a plurality of magnesium-aluminum alloy grains with grain boundaries, and a compound of one selected from consisting of magnesium and aluminum and one selected from consisting of alkaline metal and alkaline earth metal, the compound exists in the grain boundaries and is not inside but outside of the magnesium-aluminum alloy grains.