To obtain the subject dye excellent in fastness and dyeing property, not phototropic, having neutral yellow to green-yellow color tone and useful as a compounding component for controlling opaque color tone as well as a mixing component for transparent color tone.

This hydroxyquihnolone monoazo dye is expressed by formula I [R is a 1-6C alkyl, benzyl, phenyl or a 2-4C alkyl; D is benozothiazole-2-yl or a phenyl residue of formula II (either one of X1 and X2 is H, Cl, Br, methyl, a 1-6C alkylcarbonyl, cyclohexylcarbonyl, etc.; the other is H, Cl, Br or methyl; X3 is H, Cl, Br, nitro of methyl; X4 and X5 are independently H, Cl, Br, methyl, etc.)]. The dye is obtained by diazotizing a compound of the formula D-NH2 and carrying out coupling of the diazotized product with a compound of formula III. Furthermore, the dye is used for dyeing or printing a hydrophobic synthetic material at pH 8-11.