To provide an azo dye which dyes a cellulose fiber material with improved fastnesses to light and moisture by reacting a specific azo compd. with a diamine compd.

An azo compd. obtd. by reacting 1mol of a diazonium salt of an amine represented by formula I or II with 1mol of a compd. represented by formula III is reacted with an equimolar amt. of a diamine compd. represented by formula IV to give an azo dye represented by formula V [wherein D1 and D2 are each a benzene or naphthalene ring; R1 and R3 are each H, hydroxyl, etc.; R2 and R4 are each H, nitro, etc.; X is vinyl, β- sulfatoethyl, etc.; Rx, Ry, Rv, and Rw are each H or 1-4C alkyl; K1 is a group represented by formula VI, VII, or VIII; M is H or an alkali metal; m is 0-2; *connects to an azo group; R5 is H or sulfo; R6 is R5, carboxyl, etc.; K2 is a group represented by formula IX, X or XI; and A is a 2-10C linear or branched alkylene group, a 4-10C linear or branched alkylene group interrupted by 1-2 heteroatoms, a phenylene group substd. by 1-2 groups selected from among an optionally substd. 1-4C alkyl group, a 1-4C alkoxy group, and sulfo, chlorine, and bromine groups, etc.].