PURPOSE: To reduce the load of a doctor and a nurse and prevent the condensed ascites from being mixed with the filtered ascites and diluted by connecting a line recovering the filtered and condensed ascites to a filtered ascites feed line connected to the lower section of a condenser, fitting a three-way selector valve, and providing an openable/closable air vent at the upper section.

CONSTITUTION: An ascites storage container l is connected to the guide port 21 of a filter 2 via an ascites feed line 4, a filtered ascites feed line 5 is connected to one guide port 22 connected to the inside space of a hollow fiber membrane 24 via a pump 6, and the ascites from the ascites storage container 1 flows from the outside of the hollow fiber membrane 24 to the inside to be filtered. An ascites recovery line 11 connected to a recovery bag 12 is connected to a three-way selector valve 10 fitted to the filtered ascites feed line 5 connected to the guide port 31 of a condenser 3. When a valve 36 fitted to an air vent port 35 is opened and the three-way selector valve 10 is switched, the condensed ascites stored in the condenser 3 is discharged to the recovery bag 12 by the pressure head.