A photo-polymerizable ink-jet ink composition comprises a photo-polymerizable resin consisting of photo-polymerizable monomers, a photo-polymerization initiator, and a coloring material and is substantially free from a solvent. The photo-polymerizable monomers contain a hexa-functional monomer in a proportion falling within the range of 10% by weight to 30% by weight with respect to a total amount of the ink composition. The photo-polymerizable monomer other than the hexa-functional monomer is selected from the group consisting of a bi-functional monomer, a combination of a bi-functional monomer and a mono-functional monomer, a combination of a bi-functional monomer and a tri-functional monomer, and a combination of a bi-functional monomer, a mono-functional monomer, and a tri-functional monomer.