An image forming method includes ejecting an ink composition including a volatile organic solvent with a solubility parameter of 20 MPa1/2 to 25 MPa1/2, acid-functionalized polymer colloid particles with a glass transition temperature of 25° C. to 85° C., and a pigment with a surface at least a part of which is coated with a polymer, onto a non-porous substrate by an ink jet method to form an image, and the absolute value of the difference between the solubility parameter of the non-porous substrate and the solubility parameter of the volatile organic solvent of the ink composition falls within 15 MPa1/2.