Image forming method

An image forming method comprising:

• applying a treatment liquid, which contains an organic acidic compound represented by the following general formula (I), a water-soluble polymer compound, and water, on a recording medium;
• and
• applying an ink composition, which contains a pigment, a compound having a lactam structure of 5-membered ring, a compound represented by the following general formula (II), and water, on a treatment liquid-applied surface of the recording medium,
• [Chem. 1]
• CnH2n+2−m(COOH)m General Formula (I)
• wherein in the general formula (I), n represents an integer of 2 or greater and m represents an integer of 3 or greater,
• wherein in the general formula (II), 1, m, and n each independently represent an integer of 1 or greater, the relation l+m+n=3 to 15 is satisfied, and AO represents at least one of ethyleneoxy and propyleneoxy, and
• wherein the water-soluble polymer compound contains a hydrophilic structural unit having an anionic group.