In the synthesis of 2-arylamino-1, 4-naphthoquinone by the formation of 1, 4-addition of amine to 1, 4-naphthoquinone, an excess of naphthoquinone is used as there is the formation of corresponding quinone by the oxidation of additive product, substituted naphthohydroquinone. However, recovering of this by-product naphthohydroquinone or its oxidation to naphthoquinone was difficult. According to the experiment by the authors, it was advantageous to use atmospheric oxygen as an oxidizing agent with a suitable oxygen carrier. The arylaminonaphthoquinone thus synthesized dyed wool and silk red-purple as a vat dye. Also, it showed good dyeing for acetate by dispersed dyeing.