In a suction strainer, a filtration part is provided along a horizontal direction, a first end member includes a first attaching portion having a plate shape provided at a side surface of a tank, a second attaching portion provided with a filtration part, and a first hole configured to communicate a hollow part of the filtration part and the outside of the tank, the second attaching portion, the filtration part and a second end member are provided inside the tank. The second end member includes a plate-shaped part configured to cover the hollow part of the filtration part, the plate-shaped part is provided with an air vent hole, and the float is provided in such a manner that the float is movable in the horizontal direction between a position of closing the air vent hole and a position of opening the air vent hole.