The invention provides an ink composition including: (a) a polymer including a repeating unit (a1) having a group represented by the following Formula (1) and a repeating unit (a2) having a hydrophilic group; (b) a radical polymerizable compound; (c) water; and (d) a colorant; wherein, in Formula (1), each of Ra and Rb independently represents an alkyl group having from 1 to 4 carbon atoms; Ra and Rb may be bound to each other to form a 4- to 6-membered alicyclic structure; and * represents a bonding site.