The ink jet image forming apparatus has a forming device for forming an image on a recording medium, using ink containing particles including at least a colorant and a solvent, a fixing device for performing heat-fixing of the image formed by the forming device to thereby obtain a fixed image, a solvent removing device for removing the solvent in the ink forming the image before the heat-fixing by the fixing device, and a liquid coating device for coating the recording medium with a fixing assistant liquid for accelerating the heat-fixing of the image formed with the ink.