Image forming method for the photothermographic material

An image forming method comprising:

• imagewise exposing and thermal developing a sheet of photothermographic material using an image recording apparatus,
• wherein the image recording apparatus has at least the following portions (A) to (D):
• (A) a laser irradiation portion that scans the photothermographic material with a laser beam based on image data to expose the photothermographic material;
• (B) a transport portion that transports the photothermographic material in the laser irradiation portion;
• (C) a thermal developing portion, disposed on the side downstream from the transport portion, and in which a part of one sheet of the photothermographic material is imagewise exposed by the laser irradiation portion and simultaneously a part of the sheet having been already imagewise exposed is developed by heating;
• and
• (D) a guide portion, provided between the transport portion and the thermal developing portion, and allowing a flexion of the photothermographic material generated by a difference between a transport speed in the transport portion and a transport speed in the thermal developing portion:
• wherein the photothermographic material comprises at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent represented by following formula (R) and a binder on at least one surface of a support;
• wherein R11 and R11′ each independently represents an alkyl group having 1 to 20 carbon atoms, R12 and R12′ each independently represents a hydrogen atom or a group capable of substituting for a hydrogen atom on a benzene ring, L represents a —S— group or a —CHR13 — group, R13 represents a hydrogen atom or an alkyl group having 1 to 20 carbon atoms, and X and X1 each independently represents a hydrogen atom or a group capable of substituting for a hydrogen atom on a benzene ring;
• and
• wherein the photosensitive silver halide contains at least two preformed photosensitive silver halides having respective sensitivities different from each other for a light with the same exposure wavelength and a silver iodide content of the photosensitive silver halide is 40% by mole or more.