A study was carried out to detect of illegal artificial dyes and to confirm the used rate of illegal dyes in the production process of commercial jellys by thindayer chromatography and paper chromatography, from March, 1976 to July, 1976. The following conclusions were obtained 1. Seperated dyes were amaranth, erythrosin, tatrazin, sunset yellow FCF, fight green SF yellowish, fast green FCF and the most frequent use of amaranth. 2. Used rate of legal dyes were 94.12% (96 samples) and illegal dyes were 5.88% (6 samples) with samples 102. 3. The average Rf value of T.L.C. were amaranth (0.92), erythrosin (0.48), tatrazin (0.83), sunset yellow FCF(0.86), fast green FCF (0.63), light green SF yellowish (0.23) and paper chromatography were amaranth (0.76), erythrosin (0.44), tatrazin(0.75), sunset yellow FCF (0.76), fast green FCF (0.86), light green SF yellowish(0.52).