To provide a liquid force feed device having strong sapping force.

An elastic member 39 compressed through floating of a force 3 is arranged between the float 3 and a power transmission shaft 28. When a float 3 is floated, the elastic member 39 is first compressed and deformed. Thereafter, with the elastic member 39 compressed and deformed, the power transmission shaft 39 is moved upward and the snap mechanism 5 is operated to perform snap movement of a power transmission shaft 28. At a process of snap movement of the power transmission shaft 28, the compressed and deformed elastic member 39 rapidly restores deformation. The deformation restoration force of the elastic member 39 is added as a force during snap movement of the power transmission shaft 28. This constitution further increases a force generated during snap movement.