A strainer (1, 2) provided inside an injection port for injection of a liquid into a tank body, the strainer (1, 2), comprising: a strainer body (10, 10A) having a substantially bottomed tubular shape that includes a side surface (17, 17A) and a bottom surface (14, 14A), the side surface (17, 17A) including a net body through which the liquid is passable; a rod (21, 21A) having a substantially rod shape provided adjacent to the strainer body (10, 10A), the rod (21, 21A) being provided along a first direction as a longitudinal direction of the strainer body (10, 10A); a guide portion (15, 16) that regulates a moving direction of the rod (21, 21A) such that the rod (21, 21A) moves along the first direction; and a float (22, 22A) disposed on a distal end on the bottom surface side of the rod, wherein the side surface (17, 17A) includes a notched portion (17a, 17c) and a curved surface portion (17b, 17d) other than the notched portion (17a, 17c), the rod (21, 21A) is provided at a position overlapping with a circle as an extension of the curved surface portion (17b, 17d) and a position adjacent to the notched portion (17a, 17c) when viewed in the first direction, and characterized in that the side surface (17, 17A) has a substantially D shape when viewed in the first direction; the notched portion (17a, 17c) is cut away so as to form the substantially D shape; the net body being absent on the bottom surface (14, 14A), the liquid being not passable through the bottom surface (14, 14A); and the bottom surface (14, 14A) has a shape in which a part of a substantially conical shape is cut away and protrudes toward an opening of the strainer body (10, 10A), and a top of the substantially conical shape overlaps with the notched portion (17a, 17c). a strainer body (10, 10A) having a substantially bottomed tubular shape that includes a side surface (17, 17A) and a bottom surface (14, 14A), the side surface (17, 17A) including a net body through which the liquid is passable; a rod (21, 21A) having a substantially rod shape provided adjacent to the strainer body (10, 10A), the rod (21, 21A) being provided along a first direction as a longitudinal direction of the strainer body (10, 10A); a guide portion (15, 16) that regulates a moving direction of the rod (21, 21A) such that the rod (21, 21A) moves along the first direction; and a float (22, 22A) disposed on a distal end on the bottom surface side of the rod, wherein the side surface (17, 17A) includes a notched portion (17a, 17c) and a curved surface portion (17b, 17d) other than the notched portion (17a, 17c), the rod (21, 21A) is provided at a position overlapping with a circle as an extension of the curved surface portion (17b, 17d) and a position adjacent to the notched portion (17a, 17c) when viewed in the first direction, and characterized in that the side surface (17, 17A) has a substantially D shape when viewed in the first direction; the notched portion (17a, 17c) is cut away so as to form the substantially D shape; the net body being absent on the bottom surface (14, 14A), the liquid being not passable through the bottom surface (14, 14A); and the bottom surface (14, 14A) has a shape in which a part of a substantially conical shape is cut away and protrudes toward an opening of the strainer body (10, 10A), and a top of the substantially conical shape overlaps with the notched portion (17a, 17c).