An azo pigment represented by the following formula (1) or a tautomer thereof:
wherein R1 represents an aliphatic group having 1 to 8 carbon atoms in total, an aryl group having 6 to 12 carbon atoms in total or a heterocyclic group having 2 to 12 carbon atoms in total; R2 represents a hydrogen atom or an aliphatic group having 1 to 8 carbon atoms in total; R3 represents a hydrogen atom, an aliphatic group having 1 to 4 carbon atoms in total, an aliphatic amino group having 1 to 8 carbon atoms in total, or an amino group; R4 and R5 each independently represent an aliphatic amino group having 1 to 8 carbon atoms in total, or an amino group; R6 represents a cyano group, a carbamoyl group having 1 to 10 carbon atoms in total, an aliphatic oxycarbonyl group having 1 to 8 carbon atoms in total, an aliphatic sulfonyl group having 1 to 8 carbon atoms in total, or a carboxy group; and X2 represents a nitrogen atom or C-CN.