The present invention provides an image forming method for obtaining excellent color fixed images with a smaller amount of light energy. This image forming method includes the steps of: forming a toner layer of a color toner containing at least a binder resin, a coloring agent, and an infrared absorbent, on a recording medium; and fixing the toner layer by flashlight emission, where the relationship among the PAS level S of the color toner that is obtained by integrating an infrared PAS spectrum obtained through PAS (photoacoustic spectroscopy) analysis in the range of 800 nm to 2000 nm, the melt viscosity .rho. of the color toner at a reference temperature, and the energy E of the flashlight, is expressed by the following relational expression: 1000.ltoreq..rho./ES.ltoreq.5500.