To solve the problem in a conventional double drum dryer that deformation of drum surfaces caused by inclusion of hard foreign matter in sludge to be dried extends to the circumference without being limited to a local position where it is nipped, resulting in an extended deformation range, and the restoration work of the deformed part requires an extreme labor hour.

This drier has a structure in which two heated drum are arranged horizontally in opposition to each other, a sludgy matter to be dried is injected to the clearance of the two drums while rotating the two drums downward at the same speed, the drum surfaces are rotated while pressing the sludgy matter onto the drum surfaces to dry the sludgy matter, and the dried sludgy matter is scraped and peeled. Comb-tooth like irregularities are formed on the surfaces of the two drums in the drum axial direction. The irregularities are arranged so that the peaks of one comb of the drums are opposed to the bottoms of the other comb to mutually mesh the comb teeth.