PURPOSE: To obtain a disperse azo dye having excellent fastness to light, thermal fixing, pleating, washing or the like for dyeing, especially a polyester material, in a color tone from uniform yellow to violet by selecting a specified disperse azo dye.

CONSTITUTION: A disperse azo dye represented by formula {wherein R1 is H, 1-2C alkyl, halogen, NH-CO-R5 or O-SO2-R6; R2 is H, halogen, 1-4C alkyl or (halogen, CN, phenyl, -Y-1-8C alkyl or -Y-phenyl substitution) 1-8C alkoxy; R3 is (OH, CN, vinyl, phenyl, halogen, -X-phenyl or -X-1-8C alkyl substitution) 1-8C alkyl; R4 is H or R3, or R3 and N together form heterocyclic group.; R5 is (halogen, phenyl, CN or 1-3C alkoxy substitution) 1-3C alkyl; R6 is [halogen, CN or (1-4C alkyl, 1-4C alkoxy or halogen substitution) phenyl substitution] 1-4C alkyl; Y is O, S or SO2; X is O, O-CO, OCOO, COO or OCONH} is selected.