Abstract: A filter unit of type in which liquid to be filtered is made to flow from a center channel through a bottom channel to a side channel. The filter unit has enhanced air removing performance, and the residual amount of the liquid is reduced by reducing the so-called hold-up volume. A filter unit constructed such that liquid to be filtered, introduced into a housing (20) from an inlet (31) of a lid (30), is sent to a bottom channel (40) after being made to pass through a center channel (14) of a core member (13), sent to a side channel (41) from the bottom channel (40), filtered by being made to pass through a filter member (11) from the side channel (41) to radially inward, and then led to an outlet (32) of the lid (30) along the outer periphery of the core member. On the outer periphery of the core member (13), there are arranged a protrusion (15) and a recess (16). The protrusion (15) supports the inner periphery of the filter member (11) during filtration.