In a conical twin-screw extruder in which two rotor shafts having flights on the outer peripheral surfaces thereof and being adjacent to each other in the lateral direction are accommodated in a barrel having a raw material supply port on one side and a raw material discharge port on the other side, and the distance between the rotor shafts and the outside diameters of the flights thereof are gradually reduced from the supply port side to the discharge port side, characteristically, the barrel is provided with a water-removing port for removing water contained in a raw material supplied through the raw material supply port, out of the barrel. The extruder can be applied to raw materials various shapes, sizes, and properties.