The invention provides a black and white photothermographic material including, on at least one surface of a support, at least a photosensitive silver halide, a non-photosensitive organic silver salt, a reducing agent and a binder, wherein 50% or more of the total projected area of the photosensitive silver halide grains is occupied by tabular grains having an aspect ratio of 2 or more, and at least one apex portion of each tabular grain has an epitaxial junction. An image forming method is also provided, the method including bringing the photothermographic material into close contact with a fluorescent intensifying screen containing a fluorescent substance, wherein 50% or more of emission light of the fluorescent substance has a wavelength of 350 nm to 420 nm, and applying X-ray exposure. The black and white photothermographic material has high sensitivity and is superior in image storability and raw stock storability.