Thermal stability of the major color component, cyanidin 3-glucoside, isolated from Korean pigmented rice (Oryza sativa var. Suwon 415) were investigated to explore possible application of value-added natural colors as food additives. The anthocyanin showed red and blue color with maximum absorption peaks at 511 nm and 572 nm in acidic (pH 2.0) and alkaline (pH 9.0) buffer solutions, respectively, and the thermal degradation reactions were carried out with different temperature ranges at $50{sim}95^{circ}C$. Degree of degradation was determined with UV/Vis spectra which indicate characteristic absorption patterns with sharp isosbestic points at 350 nm (pH 2.0), and 275, 310, and 405 nm (pH 9.0). Thus the reaction follows simple first-order kinetics. The anthocyanin was very stable against heat at acidic pH and relatively stable at alkaline pH with half-life values of 50.3 hr and 0.6 hr at $70^{circ}C$, respectively. The activation energies and Arrhenius frequency factors of the pigment were 26.9 kcal $mol^{-1};and;6.0{ imes}10^{11};s^{-1}$, at pH 2.0, and 15.2 kcal $mol^{-1};and;1.4{ imes}10^{6};s^{-1}$, pH 9.0, and respectively.