A processing method which thermally develops a thermally developable photosensitive material which is exposed imagewise, comprising the step of thermally developing said thermally developable photosensitive material using heating element which intermittently heats and has duration time of surface temperature of not less than 250° C. to be not more than 1 second, wherein said thermally developable photosensitive material comprising a support having thereon one layer or plural layers; containing organic silver salt, photosensitive silver halide grains and a reducing agent.