To provide a sludge treatment apparatus capable of efficiently treating sludge, concentrating non-treated sludge, effectively treating excess sludge, and enhancing methane fermentation efficiency in the combination with a methane fermentation tank.

The sludge treatment apparatus is equipped with a treatment container 12, the rod-shaped ultrasonic oscillator 13 provided in the treatment container, a cylindrical screen 14 for demarcating an inner peripheral ultrasonic treatment chamber 15 in which the ultrasonic oscillator is housed and an outer peripheral treated sludge outflow chamber 18 and permeating the sludge flowing through the ultrasonic treatment chamber to permeate the ultrasonically treated sludge through the sludge outflow chamber, the sludge inflow route 16 and non-treated sludge outflow route 17 communicating with the ultrasonic treatment chamber and the treated sludge outflow route 19 communicating with the sludge outflow chamber.