Effects of ascorbic acid and citric acid on pungency and color stabilities in the Horseradish powder during 16 weeks storage were investigated. When the ascorbic arid added 0.1 wt.%, the effect of allyl isothiocynate stability was very significant after 16 weeks storage at 37$^{circ}C$. However, the effect of citric acid on the allyl isothiocyanate stability was not observed. The results also showed that ascorbic acid and citric arid did not affect the color stability of the Horseradish powder significantly. When the Horseradish powder was tempered with water, the effect of ascorbic acid on stability of allyl isothiocynate and color value was shown.