The present invention relates to a water-soluble azo compound for yellow represented by the following formula (1) ##STR00001## wherein, A represents a hydroxy group, a morpholino group, an amino group, an aliphatic amine residue which may have a substituent, an aromatic amine residue which may have a substituent, a phenoxy group which may have a substituent, or an alkoxy group which may have a substituent, R.sub.1 represents a hydrogen atom or an alkyl group having 1 to 4 carbon atoms, R.sub.2 represents a hydrogen atom, a nitro group or a hydroxy group, and n represents an integer number of 1 to 3, respectively as a free acid, and an ink composition containing the same; said ink composition has good stability and is suitable for inkjet printing; and printed matters therewith have very high fastness such as ozone fastness and the like.