UV-curable ink jet ink composition

A UV-curable ink jet ink composition comprising:

• 10.00% by mass or more and 60.00% by mass or less, relative to a total mass of the ink composition, of a compound represented by the following formula (A):
• CH2═CR1—COOR2—O—CH═CH—R3 (A)
• wherein R1 is a hydrogen atom or a methyl group, R2 is a divalent organic residue having 2 to 20 carbon atoms, and R3 is a hydrogen atom or a monovalent organic residue having 1 to 11 carbon atoms;
• 10.00% by mass or more and 50.00% by mass or less, relative to the total mass of the ink composition, of one or more monofunctional monomers having an alicyclic hydrocarbon group or a cyclic ether group;
• 0.05% by mass or more and 0.50% by mass or less, relative to the total mass of the ink composition, of one or more fluorescent brighteners including a compound represented by the following formula (b1), (b2), (b3), or (b4):
• and
• 3.50% by mass or more and 6.00% by mass or less, relative to the total mass of the ink composition, of one or more acylphosphine oxide polymerization initiators.