Heat developable light-sensitive material containing an amidine based precursor

A heat developable light-sensitive material comprising a support having thereon at least one layer containing a base precursor, a light-sensitive silver halide, a binder, and a dye-providing substance which produces or releases a diffusible dye in correspondence or countercorrespondence to the reduction of the light-sensitive silver halide to silver at an elevated temperature, said base precursor comprising a salt of a carboxylic acid and a diacidic, triacidic or tetraacidic organic base comprising a hydrocarbon group or a heterocyclic group substituted with 2 to 4 amidine groups, said amidine group substituents being obtained by removing a hydrogen atom from a group represented by formula (I-2):

• ##STR25## wherein R.sup.15 represents a substituted or unsubstituted divalent group selected from the group consisting of an ethylene group, a propylene group and a propenylene group;
• and R.sup.16 and R.sup.17, which may be the same or different, each represents hydrogen or a substituted or unsubstituted monovalent group selected from the group consisting of an alkyl group, an alkenyl group, an alkynyl group, a cycloalkyl group, an aralkyl group, an aryl group and a heterocyclic group.