PURPOSE: To enable even the fluid and low viscosity raw liquid to be pressed by mounting an elastic force feed member in the continuous screw path of a feed port for slurry-form raw liquid such as activated sludge and further providing a perforated guide member for causing subsequent raw material force feed action of said elastic force feed material and a check valve.

CONSTITUTION: A plate-form body 17 being an elastic force feed member turns subsequently along the vane surface from the beginning end part of screw blades 5 along with turning of a rotary pressing member 6 and the slurry-form raw liquid from a feed port 13 is force advanced by the sliding movement of the slide roller 18 in the bottom end part thereof, thus the liquid is subjected to ordinary pressing transfer action. Next, the raw liquid is further advanced to the transfer direction from the gap of a perforated guide member 19, and becomes the ordinary pressing- transferring state. The plate-form body 17 is again reset to the beginning end part of the screw blades by compression of a spring 15 along the guide face of the member 19. The pressed liquid is separated to filtrate 24 and cake 26 by the filter cloth 4 during pressure feeding to the outlet side. The back flow of the raw liquid is prevented by the check valve 21 in the transfer path, thus smooth pressure feeding is accomplished.