The Chinese Yam is used for various purposes (e.g., mixing it into cake or paste) because of its characteristic viscosity; it is also eaten uncooked. Conversely, the likelihood of browning limits its consumption. We, therefore, studied the prevention of browning. The absorbans based on Tyrosin was taken as the measure of the activity of Tyrosnase. The results were as follows; browning was inhibited when (1) Tyrosinase was extracted with water. (2) The P.H of grated Chinese Yam (for uncooked eating) was kept acidic, if it was preserved at 30℃?40℃. (3) The grated Chinese Yam (for uncooked eating) was kept at about 5℃ in the refrigerator; i. e., without P.H control. Mixing promoted browning when Chinese Yam is preserved longer than 4 hours.