An image forming method comprising by imagewise exposing a photothermographic material comprising at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent, and a binder, on at least one surface of a support, and thermally developing the photothermographic material at a line speed of 20 mm/sec or higher using an image forming apparatus, wherein the reducing agent is a bisphenol compound which has at a meso-position a substituent with ring structure or a substituent having an unsaturated bond.