A device for processing a photosensitive material using processing solution includes, processing chambers for storing processing solution therein, at least one of the processing chambers being lower than another processing chamber, a bypass for placing each processing chamber that is downstream of another processing chamber relative to conveyance direction of the photosensitive material in fluid communication with the another processing chamber to pass the processing solution therethough, and a check valve disposed at each bypass for allowing the processing solution which flows from the processing chamber disposed downstream relative to conveyance direction of the photosensitive material to the another processing chamber, and for preventing the processing solution from flowing from the another processing chamber to the downstream processing chamber. The valve body of the check valve, which has a specific gravity different from a specific gravity of the processing solution, is urged against the valve seat by buoyant force.