A filter unit includes: a space portion, through which a liquid passes, whose outer cross-sectional shape when cut along the direction orthogonal to the axial direction is circular or polygonal; a filter provided at the surface on one end side of the space portion in the axial direction thereof; a protruding member, provided at the surface on the other end side of the space portion in the axial direction thereof, that protrudes toward a center area of the surface on the one end side of the space portion; an inflow channel that allows the liquid to flow into the space portion from a direction tangential to the side circumferential surface of the space portion; and an outflow channel that allows the liquid to pass through the filter and flow out from the space portion.