To provide a liquid pumping device having a simple structure in which an air supply valve element and an up-and-down rod are hardly tilted.

In the liquid pumping device 1, a working fluid introducing port 11, a working fluid discharge port 13, a liquid inlet port 16 and a liquid discharge port 17 are disposed in a sealed vessel 2, and the opening and closing of an air supply valve 18 of the working fluid introducing port 11 and an exhaust valve 19 of the working fluid discharge port 13 are switched in response to a height of a liquid level of liquid stored in the sealed vessel 2. A through-hole 21a is formed in an air supply valve body 21, and the upper part of the up-and-down rod 22 for opening the air supply valve body 21 is disposed penetrating through the through-hole 21a of the air supply valve body 21. The lower part of the lifting bar 22 located at the lower part of the air supply valve body 21 is guided up and down by a lower part guiding member 20a, and the upper part of the lifting bar 22 located at the upper part of the air supply valve body 21 is guided up and down by an upper part guiding member 23.