The present invention provides a fixing method with good fixing sensitiveness, a fixing device, an image forming method and an image forming device. The methods and the devices thereof can not only damage resin particles of a resin containing toner or the like on media such as paper, but also fix the resin particles on the media rapidly after coating the fixation liquid on the media which is adhered with the resin particles. Foamed fixation fluid containing soft agent is put onto the resin particles on the media according the fixing method of the present invention, the resin particles are fixed on the media, and the soft agent leads at least part of resin to dissolve or swell to soften the particles containing resins. The fixing method of the present invention can also control the membrane thickness of the foamed fixation liquid, so as to lead the time of the foamed fixation liquid put onto the resin particles on the media to be equal to or longer than the permeation time of the foamed fixation liquid which put onto the resin particles permeating onto the resin particles layer to the media.