To provide a liquid pumping device changing over an air supply valve to be opened/closed in a well responsive manner while preventing the inclination of an air supply valve body and a lifting rod.

The liquid pumping device 1 comprises a sealed container 2 having an operating fluid introduction port 11, an operating fluid drain port 13, a liquid flow-in port 16 and a liquid drain port 17, wherein the air supply valve 20 in the operating fluid introduction port 11 and an exhaust valve 21 in the operating fluid drain port 13 are changed over to be opened/closed depending on the liquid surface level of liquid staying in the sealed container 2 so that, at first, the exhaust valve 21 is opened and the air supply valve 20 is closed for the liquid to flow from the liquid flow-in port 16 and then the exhaust valve 21 is closed and the air supply valve 20 is opened for the liquid staying in the sealed container 2 to be pumped from the liquid drain port 17. A lower lifting rod 18b is integrally mounted on the air supply valve body 23 of the air supply valve 20 so as to be guided up and down by a lower guide member 19b, and an upper lifting rod 18a is integrally mounted on the air supply valve body 23 of the air supply valve 20 so as to be guided up and down by an upper guide member 19a.