The invention provides a treatment liquid for ink jet, which includes at least an organic acid having a pKa value of 4.5 or less, a nonionic substance, and water, wherein: (I) the treatment liquid has a pH value of 1.5 to 5.5, (II) the nonionic substance has a weight-average molecular weight of 300 or more but less than 5,000, and (III) a difference in solubility parameter (SP value) between a fundamental skeleton part of the organic acid excluding its acid group and the nonionic substance is 0.01 to 0.75.