A method for preserving an ink-jet, including a step of: keeping the ink-jet ink in a sealed container having a ratio of water of 1.50 to 5.00 weight % measured with Karl-Fischer method in an inside portion of the sealed container, wherein the ink-jet ink includes a cationic polymerizable monomer and an initiator, and the ink-jet ink is curable by irradiation with an active energy ray.