A photothermographic material having, on at least one side of a support, an image forming layer including at least a photosensitive silver halide, a non-photosensitive silver salt of a fatty acid, a reducing agent, and a binder, wherein 1) the photosensitive silver halide has an average silver iodide content of 40 mol % or higher, and 2) the photothermographic material includes a compound represented by the following formula (I) or a salt thereof: R.sub.1--C.ident.C--R.sub.1' Formula (I) wherein R.sub.1 and R.sub.1' each independently represent a hydrogen atom, or a substituted or unsubstituted alkyl group, aryl group, or heterocyclic group, and R.sub.1 and R.sub.1' are not simultaneously a hydrogen atom. The invention provides a photothermographic material which exhibits high sensitivity and excellent image storability, and an image forming method.