The present invention provides an image forming method using an image recording apparatus that includes a laser irradiating means for laser scanning of a photothermographic material that has a support and includes on at least one surface thereof a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder, and a conveying means for guiding the photothermographic material in a sub-scanning direction to a thermal development unit, wherein the reducing agent is a specific bisphenol compound. The invention also provides another image forming method including carrying out thermal development, with an interval time equal to or less than 12 seconds, of the photothermographic material.