PURPOSE: To enable highly viscous slurry to be transported under small pressure differential by discharging the gas injected in the upper course of a pipeline at intermediate parts of the pipeline while adjusting a ratio of gas volume to flow rate in the pipeline within a fixed range.

CONSTITUTION: In the transportation of highly viscous slurry, a fixed amount of gas is injected from a supply source 6 into the upper course of the pipeline 7, and a fixed amount of the injected gas is devised to be discharged through exhaust valves 9 at intermediate parts of the pipeline 7. Thus, the trnsportation of slurry by pipeline can be achieved under relatively small pressure differential by transporting slurry while adjusting a ratio of gas volume to flow rate in the pipeline 7 within a fixed range.