To provide a producing method of a solid treating agent for a silver halide photographic sensitive material, especially a tablet-type solid treating agent, which is produced by using a compsn. containing alkali metal hydroxides and which shows excellent dimensional stability against reduction of hardness and moisture absorption of tablets even after stored for a long time, especially stored under high temp. and high humidity conditions.

In the production of a solid treating agent containing alkali metal hydroxides for a silver halide photographic sensitive material, these that are at least 50 wt.% of the whole alkali metal hydroxides have 2000 μm to 37 μm particle size. Therefore, by controlling the particle size, kinds and production conditions of the alkali metal hydroxides to be added, the dimensional stability of the agent can be improved even under high temp. and high humidity conditions.