BACKWASH FILTERING DEVICE

PROBLEM TO BE SOLVED: To provide a backwash filtering device having excellent treatment capacity of raw water and capable of effectively removing microorganisms lodged in a filtering element.SOLUTION: The backwash filtering device includes a pressure container and the cylindrical filtering element arranged within the pressure container. Raw water is made to pass from inside of the filtering element toward outside for filtration, and filtering water is made to flow back to clean the filtering element. The filtering element is constituted by laminating disk-shaped filtering materials each having a filtering flow passage forming groove formed radially to form filtering flow passages between the upper and lower filtering materials. The flow passage height of the filtering flow passage on the downstream side is set higher than that on the upstream side.