PURPOSE: To prevent the clogging by supporting and racking a screen drum so as to be freely rotatable and opening an original solution supply line formed in a feed shaft in the screw drum, in a screw press for compress-sending and dehydrating sludge, etc.

CONSTITUTION: In a screw press for supporting and racking so as to be freely rotatable a cone-like feed shaft 3 in which a carrying spiral blade 4 is wound round to its peripheral surface in a cylindrical screen drum 1, and for compress- sending and dehydrating sludge, etc., supplied to its one end to the other end, the screen drum 1 is supported and racked against the feed shaft 3, and an original solution supply line formed in the feed shaft 3 is opened in the screen drum 1. In such a way, by rotating the screen drum 1, the operating is executed, while reproducing its mesh, therefore, the continuous operation being free from clogging is executed.