To provide a method for dewatering scum discharged in a papermaking process without using chemicals.

The dewatering method for the scum discharged in the papermaking process removes water from the scum containing water in sludge such as sewage separated from white water used in the papermaking process. The scum is supplied into a bottom-opened concave rotary vessel 12 through a supply pipe extended from below the vessel upward and scattered by keeping a contact with a top plate 121 of the rotating rotor 12 to deposit the sludge on the side face 122 of the rotor 12 while dropping water downward along the side face 122 of the rotor 12 to separate the sludge and the water.