A submerged processing device for a photosensitive material disposed at a partitioning wall which is provided within a processing tank main body and which is between processing chambers respectively storing a processing liquid, the submerged processing device includes: a housing at an interior of which is formed a processing space where the processing liquid is stored; a conveying path for conveying-in of the photosensitive material and which is formed in the housing so as to communicate with an interior of the processing space; a path for conveying-out of the photosensitive material and which is formed in the housing so as to communicate with the interior of the processing space; a processing liquid passage preventing mechanism disposed at the photosensitive material conveying path such that only the photosensitive material passes therethrough; and a processing liquid changing mechanism provided at the housing, for changing the processing liquid stored in the processing space.