Ethyl acetate extracts of 6 commercial amaranths produced in 1985 and 1986 were analyzed with a gas chromatograph. The ${alpha}$-naphthylamine ranging from 142 ppb to 4216 ppb was detected, but the ${eta}$ naphthylamine was not detected. The mutagenicity of the ethyl acetate extract was tested using Salmonella typhimurium TA100 in the presence of the S-9 fraction. Significant mutagenic activity was seen in samples containing high levels of ${alpha}$-naphthylamine. It is suggested that the potential hazard of amaranth to the general public should be reconsidered from the point that the impurities contained in amaranth preparations are the main sources of mutagenicity or carcinogenicity.