An azo compound represented by the following Formula (1) or a salt thereof, and an ink composition comprising the same ##STR00001## (wherein, each of R.sup.1, R.sup.2, R.sup.5, R.sup.6 and R.sup.7 independently represents a hydrogen atom, a carboxyl group, a sulfo group and the like, each of R.sup.3 and R.sup.4 independently represents a hydrogen atom, a sulfo group, a nitro group, a (C1 to C4) alkyl group (which may be substituted by a hydroxyl group or a (C1 to C4) alkoxy group), a (C1 to C4) alkoxy group (which may be substituted by a hydroxyl group, a (C1 to C4) alkoxy group, a sulfo group or a carboxyl group) and the like, and n represents 0 or 1, respectively).