PURPOSE: To eliminate leakage of liquid, by feeding a liquid in one container under pressure by a pressurized gas while receiving the liquid returned from a load into the other container, and eliminating mechanical parts subjected to friction.

CONSTITUTION: A container 1 is used as a container for receiving liquid returned from a load. In the state that stop valves V2, V4, V5 and V7 are closed and stop valves V1, V3, V6 and V8 are opened, liquid returned from the load is carried into the container 1 via the valve V3. On the other hand, a pressurized gas is introduced into another container 2 via the stop valve 6, so that pressure in the container 2 is raised. Here, since the liquid is carried to the load under pressure via the valve V8 and a pressurized conduit 2b, mechanical parts subjected to friction can be eliminated and production of foreign matter can be avoided. Therefore, it is enabled to eliminate the leakage of liquid.