Dergree of gelatinization during cooking of Akibare(Janponica) and Milyang 23(Indica) rice was determined by X-ray diffractometry using a buit-in internal standard approach. The metod had a total coefficient of Variation of 99.9%. Milyang 23 showed slightly higher degree of gelatinization than Akibare during cooking at $100^{circ}C$. Both rice was completely gelatinized after 20 minute cooking.