To prevent suction of air from a liquid inlet of a suction pipe in sucking a liquid in a tank through a liquid sucking pipe.

Inlets 4b, 5b of the liquid sucking pipes 4, 5 are opened upward, and a float valve element 9 moved up and down with the vertical displacement of the liquid level in the tank is disposed on the upper side of the inlet of the liquid sucking pipe, whereby before the liquid level becomes lower than the inlet, the inlet is air-tightly closed by the lowered float valve element.