To provide a method for preparing the silver salt of an organic acid giving a heat developable image recording material having high sensitivity and high stability of an image after heat development.

In the method for preparing the silver salt of an organic acid in which an aqueous solution containing silver ions is reacted with a solution containing an alkali metallic salt of the organic acid in a hermetically sealed mixing means, the silver ion solution is supplied to a reaction field solution in a stage before the mixing stage and then the alkali metallic salt solution is supplied to the reaction field solution or the hermetically sealed mixing means.