To provide: a cationic polymerization curing-type inkjet ink capable of suppressing a dot fluctuation and printing twist by an ink thickening caused due to a dark reaction or by a change in the ink delivered amount caused due to the deterioration of ink-repellent property on a nozzle surface subjected to an ink-repellent treatment, during a long-term storage thereof without lowering curing sensitivity to secure stable delivering property even during a long-term storage thereof; and an image forming method.

This cationic polymerization curing-type inkjet ink is an inkjet ink used for an inkjet head of which nozzle plate has been subjected to an ink-repellent treatment comprising a cationic polymerizable compound, a cationic polymerization initiator, a coloring material, and a primary alkylamine compound having a total carbon number of 14 or more and 20 or less.