Filter device (10) is provided with a head (20), a filter element (40), and a housing (30). The head (20) is provided with an inlet (24) which is attached to a hydraulic circuit (5), and into which flows the operating oil (L1) that is to be filtered. The filter element (40) filters the operating oil (L1) that is to be filtered. The housing (30) has an opening (30b) through which the filter element (40) passes, and which holds the filter element (40) inside it. The filter element (40) is provided with an element main body (48), and an element pressing part (47). The element pressing part (47) is provided to the element main body (48). The element pressing part (47) is provided with a contact part (53) that can be shifted toward or away from the inner surface (30a) of the housing (30). A groove (35) that holds the contact part (53) is provided to the housing (30). The contact part (53) can be shifted until it comes out of the groove (35).