To transport liquid continuously using a compressed gas.

An inflow discharge vessel 20 consisting of a pipe stretching in the vertical direction is installed under the liquid surface, and its bottom is put in communication with the inflow end part of a liquid transport pipe 16 and also put in communication under the liquid surface through a check valve 22 in the inflowing direction. One end of a gas supply/discharge pipe 24 is put in communication with the top of the vessel 20, and the other end is diverged in two, one of which is arranged as leading to a compressed gas source 28 via a gas supply valve 26 while the other leading to the atmosphere via a gas discharge valve 30. A compressed gas is supplied to the vessel 20 and expanded to that αm becomes greater than α, where αm represents the max. acceleration applied to the liquid in the transport pipe 16 resulting from a sink of the liquid level in the vessel 20, while α represents the acceleration acting on the liquid level by the liquid in the pipe 16, and then the liquid is sent by pressure to the discharge side. The gas is discharged from the vessel 20 until the flow speed due to inertia of the liquid in the pipe 16 is damped to nullify, and at the same time, liquid is allowed to flow in via the check valve 22 so that the liquid surface rises, and again the compressed gas is supplied.