To provide a radiation-curable ink composition that can form a high-quality image on not only liquid absorbing materials to be recorded but also non-liquid absorbing materials to be recorded, is superior in curing properties in air, and is superior in storage stability, color tone, light fastness and water resistance of ink, and also to provide an image recording method. The radiation-curable ink composition comprises a monomer having a polymerizable group selected from the group consisting of an acryloyl group, a methacryloyl group, an allyl group, and a vinyl group, an oil-soluble dye, and from 0.005 to 1% by weight of a storage stabilizer, wherein the oil-soluble dye is dissolved in the ink.