PURPOSE: To lighten the conventional work load for inserting and recovering a polymer pig and feeding and discharging cleaning water and to reduce the total time for cleaning by using this device.

CONSTITUTION: One end 2 of a pipeline 1 is connected to a process liq. inlet pipe 3 and the other end 4 to a process liq. outlet pipe 5 respectively through valves V1 and V2, and vessel 6 and 7 for receiving a globular polyurethane foam are connected respectively to both ends 2 and 4 through the valves V1 and V2. A couple of cleaning soln. feed valves V3, V4 and V5, V6 are provided to the valves 6 and 7, and the globular polyurethane foam 8 is placed in the pipeline 1. Water is sufficiently discharged through a net 9 furnished to the vessel.