<p>A filtration device (10) has a head (20), a filter element (40), and a housing (30). The head (20) has an inflow path (24) connected to a liquid pressure circuit (5) and into which hydraulic oil (L1) to be filtered flows. The filter element (40) filters the hydraulic oil (L1). The housing (30) has an opening (30b) through which the filter element (40) passes and receives in it the filter element (40). The filter element (40) has an element body (48) and an element pressing section (47). The element pressing section (47) is provided at the element body (48) and has a contact section (53) displaceable in the direction approaching and departing from an inner surface (30a) of the housing (30). A groove (35) for receiving the contact section (53) is formed in the housing (30). The contact section (53) is displaceable until it is out of the groove (35).</p>
