Ink jet ink composition and image forming method

An ink jet ink composition comprising:

• water;
• and
• particles including a chain polymer including Structural Unit (1), Structural Unit (2), and a hydrophilic group and a polymerizable group,
• in Structural Units (1) and (2), Cy1 and Cy2 each independently represent a divalent organic group having 3 to 30 carbon atoms including a cyclic structure, Y1 and Y2 each independently represent an oxygen atom, a sulfur atom, or a —NR1— group, R1 represents a hydrogen atom or a hydrocarbon group having 1 to 10 carbon atoms,
• *1 in Structural Unit (1) represents a bonding position to a structural unit other than Structural Unit (1), and *2 in Structural Unit (2) represents a bonding position to a structural unit other than Structural Unit (2).