Abstract: An apparatus for treating sludge deposits comprising a girder, first running means for moving the girder in a direction perpendicular to the longitudinal direction of the girder, kneading means held on the girder, second running means for moving the kneading means through a holding frame in a direction perpendicular to the longitudinal direction of the girder and lift means for bringing up and down the kneading means while a chemical is fed from the kneading means is disclosed.The method for treating sludge deposits by using this treating apparatus comprises repeating the step of treating a sludge deposit layer in a band-like area by simultaneously driving the second running means and lift means and the step of driving the first running means, whereby a sludge deposit in a broad region is continuously and promptly treated.