An automatic developing machine for developing photosensitive material while feeding the photosensitive material through a feed path through which developing solution is circulated. The feed path has a narrow, slit-shaped section. The feed path is defined between a pair of opposed wall members, one of which can be disassembled from the other. The members planted with fiber are detachably fitted on guide surfaces of the wall members which face an emulsion surface of the photosensitive material.