PURPOSE: To obtain an automatic developing machine which is made compact, and where anti-pollution and manpower saving are executed and the quality of development in progress is not adversely affected by deteriorated processing solution.

CONSTITUTION: This automatic developing machine is provided with a replenishing device 8 for the solid processing agent for replenishing 24 for keeping the performance of the processing solution in the automatic developing machine for consecutively processing a photosensitive material constant. A supply tray for storing the processing agent 24 is provided to be opposed to the liquid level of a processing agent replenishing tank (sub tank) 20, and throws in and supplies the solid processing agent one by one at a place in the sub tank 20 where the flow velocity of circulating liquid current is high or vortex occurs. In the case of receiving a throw-in signal, the specified number of solid processing agents 24 are thrown in and drop in the sub tank 20 so as to be solved nearly in an instant.