A liquid developer includes a carrier liquid, and a toner particle which contains a resin having an unsaturated double bond, a compound represented by the formula (I) and a photopolymerization initiator and whose surface is treated by a polyamine, wherein m and n each independently represent an integer of 1 to 10,000; m+n represents an integer of 10 to 10,000; and R1, R2, and R3 each independently represent a single bond or a divalent aliphatic hydrocarbon group having 1 to 12 carbon atoms.