A photothermographic material including, on one side of a support, an image forming layer containing at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder, and, on the other side of the support, a non-photosensitive back side layer. The total quantity of an alkaline earth metal contained in the non-photosensitive back side layer is 1.times.10.sup.-5 mol/m.sup.2 to 1.times.10.sup.-3 mol/m.sup.2.