To eliminate the wrinkles of a processing sheet easily generated at the time of carrying a silver halide photosensitive material and the processing sheet which are stuck to each other, on heating plates.

The developing processor forms an image in such a manner that a film and the processing sheet which are stuck to each other are carried along the surfaces of the heating plates 68A-68E of a thermal developing part 66, to be heated. At this time, heaters 69F-69J in the central parts of the heating plates 68A-68E are set to be temp. suitable for development processing and heaters 69A-69E and 69K and 69O in both end parts are set to be the temp. higher than that of the heaters 69F-69J in the central parts by a fixed temp. Thus, heating is executed in a state where differences in the temp. are made between the central parts and both end parts in the heating plates 68A-68E. Since the expansion of both end parts is greater than that of the central part, in the processing sheet, thermal development processing is attained in the state where the processing sheet and the film are closely stuck, without generating the wrinkles in the processing sheet.