A filter device provided in a tank, comprising: a casing disposed inside the tank and having a substantially bottomed cylindrical shape; an inflow portion configured to cause liquid to flow into the casing; a lid (12; 12-1; 12-2) covering an upper face of the casing and an upper face of the tank; a filter element disposed inside the casing and including a filtration member that has a substantially hollow cylindrical shape, a lower plate covering a lower end face of the filtration member, and an upper plate covering an upper end face of the filtration member; and an outflow portion provided in such a manner as to penetrate the lower plate and a bottom face of the casing and communicate with a hollow portion of the filtration member and an inside of the tank, the filter device being characterized in that: the upper plate is abutted with a lower face of the lid (12; 12-1; 12-2), a first through-hole is formed in a substantially center of the upper plate, in a plan view, a second through-hole (12a; 12a-1; 12a-2), in which a first opening being one end is disposed at a position overlapped with the first through-hole, and a second opening (12c; 12c-1; 12c-2) being the other end is disposed between a side face of the tank and a side face of the casing, is formed in the lid (12; 12-1; 12-2), and the first through-hole and the second through-hole (12a; 12a-1; 12a-2) communicate with the hollow portion of the filtration member and space that is inside the tank and outside the casing. a casing disposed inside the tank and having a substantially bottomed cylindrical shape; an inflow portion configured to cause liquid to flow into the casing; a lid (12; 12-1; 12-2) covering an upper face of the casing and an upper face of the tank; a filter element disposed inside the casing and including a filtration member that has a substantially hollow cylindrical shape, a lower plate covering a lower end face of the filtration member, and an upper plate covering an upper end face of the filtration member; and an outflow portion provided in such a manner as to penetrate the lower plate and a bottom face of the casing and communicate with a hollow portion of the filtration member and an inside of the tank, the filter device being characterized in that: the upper plate is abutted with a lower face of the lid (12; 12-1; 12-2), a first through-hole is formed in a substantially center of the upper plate, in a plan view, a second through-hole (12a; 12a-1; 12a-2), in which a first opening being one end is disposed at a position overlapped with the first through-hole, and a second opening (12c; 12c-1; 12c-2) being the other end is disposed between a side face of the tank and a side face of the casing, is formed in the lid (12; 12-1; 12-2), and the first through-hole and the second through-hole (12a; 12a-1; 12a-2) communicate with the hollow portion of the filtration member and space that is inside the tank and outside the casing. the upper plate is abutted with a lower face of the lid (12; 12-1; 12-2), a first through-hole is formed in a substantially center of the upper plate, in a plan view, a second through-hole (12a; 12a-1; 12a-2), in which a first opening being one end is disposed at a position overlapped with the first through-hole, and a second opening (12c; 12c-1; 12c-2) being the other end is disposed between a side face of the tank and a side face of the casing, is formed in the lid (12; 12-1; 12-2), and the first through-hole and the second through-hole (12a; 12a-1; 12a-2) communicate with the hollow portion of the filtration member and space that is inside the tank and outside the casing.