To obtain an ink composition having high durability and an ink set containing the ink composition and capable of being suitably used for an inkjet printer.
The ink composition contains at least one of water-soluble dyes represented by formula (1) (wherein A is any one of hydrogen atom, chlorine atom, methyl group, amino group, hydroxy group, nitro group, carboxyl group or an alkali metal salt thereof, or a sulfonic acid group or an alkali metal salt thereof; X and Y are each independently hydrogen atom or an alkali metal atom; (x) and (y) are each independently an integer of 1 to 3; and (z) is an integer of 1 or 2), water as a main solvent wherein the specific resistance value is at least not less than 3 kΩ/cm; a water-soluble organic solvent having a boiling point of not less than 100°C as a side solvent; and a divalent metal ion.
FUJII ICHIRO
MOTOYAMA KIYOTO
NAKAMURA MASA
KOJIMA MASAYOSHI
KAJIURA NORIKO
NIPPON KAYAKU KK