A filter element having a substantially cylindrical shape is provided inside a filter case that is provided with a plurality of opening portions in a side surface and has a bottomed substantially cylindrical shape. A fluid flows into a hollow portion of the filter element from an inflow portion provided between a bottom surface of the filter case and the filter element in a height direction. Further, an inner tube provided inside a filtration material having a substantially cylindrical shape includes a first region that is formed with an opening portion substantially on the entire surface and a second region that is not formed with an opening portion. The second region is provided below the first region to include a lower end of the inner tube.