The present invention relates to a water-soluble azo compound or a salt thereof represented by the following formula (1): ##STR00001## (wherein, R represents a hydrogen atom, an alkyl group having 1 to 4 carbon atoms, an alkoxy group having 1 to 4 carbon atoms or a sulfo group, n, m, x and y represent an integer of 1 or 2, 1 to 3, 2 to 4 and 1 to 3, respectively.) and an ink composition containing the same; the above compound or a salt thereof has a hue possessing a high vividness suitable for inkjet recording, provides various fastnesses to recorded matters, and is useful as a yellow coloring matter excellent in storage stability when prepared into an ink composition, and suitable for ink compositions, especially inks for inkjet recording.