To provide a method for preparing particles of a silver aliphatic carboxylate excellent in the ability to prevent fog and the ability to prevent the fog with time and further image stability after heat developing treatment and light transmissivity when used as a heat developing image recording material.

This method for producing a silver aliphatic carboxylate is to carry out a reaction in the presence of a synthetic water-soluble polymer at ≥5°C and ≤60°C temperature in the method for producing a silver aliphatic carboxylate comprising reacting a silver ion-containing solution in water or a mixture of water with an organic solvent as a solvent with an alkali metal aliphatic carboxylate-containing solution in water, an organic solvent or a mixture of water with the organic solvent as a solvent.