An azo dye represented by the following formula (I): wherein, in formula (I), R1, R2, R3, and R4 each independently represent a hydrogen atom, an aliphatic group, an aryl group, a halogen atom, an acyl group, a cyano group, an acylamino group, an aliphatic oxycarbonyl group, an aryloxycarbonyl group, a carbamoyl group, an aliphatic sulfonyl group, an arylsulfonyl group, a sulfamoyl group, an aliphatic oxycarbonylamino group, an aryloxycarbonylamino group, a sulfo group, a carboxyl group, a carbamoylamino group, a sulfamoylamino group, or an aliphatic- or aromatic-sulfonylamino group, wherein R1 and R2 and/or R3 and R4 may be combined with each other to form a five- or six-membered aromatic ring or non-aromatic ring; X represents a carbon atom or a nitrogen atom, wherein n is 0 when X is a nitrogen atom and n is 1 when X is a carbon atom; A, B, C, and D each represent a carbon atom or a nitrogen atom, provided that at least one of A, B, C and D represents a nitrogen atom; Y represents a substituent; and m denotes an integer from 0 to 3.