To provide a liquid pumping device in which the downward movement of an up-and-down rod makes an air supply ball valve element move downward by preventing the air supply ball valve element from pivoting at a position where the air supply ball valve element opens an air supply valve port.

In the liquid pumping device 1, a working fluid supply port 11 and a working fluid discharge port 13, and a fluid inlet 16 and a fluid outlet 17 are provided to a hermetic container 2, and the opening and closing of an air supply valve 20 at the working fluid supply port 11 and an air release valve 21 at the working fluid outlet 13 are changed over according to the height of the liquid level of the liquid stored in the hermetic container 2. The air supply ball valve element 21 is disposed on the working fluid supply port side 11 of the air supply valve port 24, and the up-and-down rod 22 for openably operating the air supply ball valve element 21 is disposed so as to extend through the air supply valve port 24. A conical spring 23 gradually reduced in diameter downward is provided to press the air supply ball valve element 21 in the direction in which the air supply valve port 24 on the lower side is closed. The up-and-down rod 22 is vertically guided by an upper guide member 20a and a lower guide member 20b.