In the previous paper we reported that natural indigo products can be discriminated from synthetic indigo products by detecting red pigments contained as contaminants in indigo dyestuffs by means of HPLC. However, the HPLC method is difficult to put into practical use due to the high cost of equipment. Herein, the capability of TLC to discriminate between the two was investigated. The red pigment contained as a contaminant only in sukumo, Japanese natural indigo dye, and another red pigment contained as a contaminant only in synthetic indigo could be separated and detected on TLC. This means that the simple TLC method is capable of discriminating between natural indigo dyeing and synthetic indigo dyeing.