Filter device

When air inside a filter device is purged, filtered liquid can be discharged together with air to the outside of the filter device. A casing is provided inside a tank, a filter element is provided inside the casing, and a lid is provided so as to cover the upper face of the casing and the upper face of the tank. A first through-hole is formed in the substantially center of an upper plate that covers the upper end face of a filtration member of a filter element and is abutted with the lower face of the lid; in a plan view, a second through-hole, in which a first opening being one end is disposed at a position overlapped with the first through-hole, and a second opening being the other end is disposed between the side face of the tank and the side face of the casing, is formed in the lid; and the first through-hole and the second through-hole communicate with the hollow portion of the filtration member and space that is inside the tank and outside the casing.