PURPOSE: To obtain a novel dye, with a specific molecular structure containing plural diazonaphthalenyl groups, which exhibits an excellent dichroism of bluish red to bluish green colors and is suitable for the preparation of a light-polarizing film based on polyvinyl alcohol.

CONSTITUTION: An optionally substituted aromatic amino compound (e.g. 4-nitro- o-sulfanylic acid) is diazotized and coupled with 4-hydroxy-7- aminonaphthalene-2,8-disulfonic acid or the like added, the obtained product is boiled in an aqueous solution containing hydrochloric acid to separate a sulfo group and the resulting product is diazotized followed by coupling with 4-amino-5-hydroxynaphthalene sulfonic acid or the like to obtain the aimed novel dichroic dye for a light-polarizing film represented by the formula [wherein (n) is 1 or 2; A is (substituted) aryl or a heterocyclic ring; R1 and R3 are each H or SO3H; R2 is H, NH2, NH-acyl, etc.; R4 is H, OH, alkoxy, etc.; R5 is OH or NH2; and X is Cl, SO3H or H].