The anthocyanin compounds in purple sweet potato make this kind of food very interesting to be developed into natural dyes by adding copigment to increase the color stability. The purpose of this study was to determine the anthocyanin stability of purple sweet potato extract as a natural coloring by the addition of sodium caseinate copigment in various heating temperatures and irradiation time. The characteristics of anthocyanin extract of purple sweet potato obtained then analyzed for water content, extract yield, acidity, total anthocyanin, polyphenols, and color intensity. Then the characteristics of purple sweet potato extract with the addition of sodium caseinate copigment in different concentrations were tested. The results show that the purple sweet potato extract had a water content of 24.29%, extract yield of 22.46%, acidity of 5.51, total anthocyanin of 422.47 mg/L, polyphenols of 10.24 mg/L, and color intensity ohue of 86.42367 which is the red and yellow (YR). For purple sweet potato extract with the addition of copigment, the color stability test was stable on various heating temperatures as the ohue value remains in the red-yellow (YR) range with the color even increased to red (R). For stability to irradiation, ohue values are in the range of red and yellow (YR). Stability testing was also stable in various irradiation as maintain color was still red-yellow (YR).