A method and apparatus for forming an image which can form a high-quality image on a great variety of print media regardless of the surface roughness or ink absorptivity of the print medium, without sacrificing the high degree of freedom of the ink jet printing system are provided. An ink jet printing section ejects ink to an intermediate transfer body to form an ink image on the intermediate transfer body. Before the ink image thus obtained is transferred to a print medium, an ink transfer adjuvant is applied to the print medium. Then, the ink image formed on the intermediate transfer body is transferred to the print medium to which the ink transfer adjuvant has been applied.