To provide a silver salt photothermographic dry imaging material which reduces internal contamination of a thermal development apparatus by a volatile substance during development, and excels in image preservability after development, and also to provide a development method of the same.

The silver salt photothermographic dry imaging material has on a support at least a photosensitive layer, a light-insensitive layer and a protective layer, wherein a mass reducing value from 25°C to 100°C by a heat drying mass measurement of the silver salt photothermographic dry imaging material is ≤0.4% based on a mass value at 25°C. The development method of the same is also provided.