PURPOSE: To supply a solid processing agent in accordance with the amt. of a photosensitive material by controlling the capacity of the processor to a specified level.

CONSTITUTION: The amt. of a photosensitive material to be processed by one solid processing agent 1, the time required to dissolve the agent and the number of the agents to be supplied during the time are imputted to a processing agent supply controlling means 109, the amt. of the photosensitive material to be processed per hour and further the number of the processing agents to be supplied per hour are calculated according to an operational program previously incorporated, and the supply signal is outputted to a means for extruding the processing agent to supply the agent to a filtration part 114.