PURPOSE: To perform titled dehydration continuously and surely by the attaching and detaching motions of a press plate to an upper roller, and the force meshing thereof into between dented upper and lower rollers.

CONSTITUTION: A press plate 6 which is formed in an arc shape in a way as to be in proximity to part of the outside circumference of an upper roller 1, is a movable system, is of a hurdle shape or has many dehydrating holes or slits, is disposed on the bottom surface of said roller. One end of the plate 6 is provided freely oscillatably to a frame F via a shaft 7. Screen dregs are supplied continuously onto the plate 6, and are subjected to primary dehydration by the contact under pressure to the roller 1 surface of the plate 6, whereby they are made less bulky. Thence, they are forcibly meshed between the revolving rollers 1 and 2 provided with grooves 1a, 2a, whereby they receive desired secondary dehydration. The screen dregs stuck on the lower roller 2 are scraped off by a scraper 5.