The utility model aims to provide a filtering device which can supply raw water evenly for filtering tanks and can easily ensure architectural strength with regards to the design of a raw water supply part. The filtering device is provided with the raw water supply part (3), the upflow filtering tanks (2a, 2b and 2c) and raw water passages (4a, 4b and 4c), wherein the upflow filtering tanks are arranged in parallel in the X direction and are provided with floating filter material layers respectively; and the raw water passages supply raw water from the raw water supply part (3) to the filtering tanks (2a, 2b and 2c) by crosshead. The filtering device is characterized in that the raw water supply part (3) is water tanks arranged in parallel on the filtering tanks (2a, 2b and 2c); the bottom surface of the raw water supply part is supported by a ground disk; all overflow parts (41a, 41b and 41c) are arranged in a position which is higher than the specified height relatively to the waterhead surfaces of the filtering tanks; the raw water passages (4a, 4b and 4c) are provided with the overflow parts (41a, 41b and 41c), pressure-regulating parts (42a, 42b and 42c) and raw water inlets (44a, 44b and 44c); raw water overflows from the upper part of the raw water supply part (3); the pressure-regulating parts (42a, 42b and 42c) extend downwards from the overflow parts (41a, 41b and 41c); and raw water is injected from the lower parts of the filtering tanks (2a, 2b and 2c).