To provide a solid-liquid separator in which a treatment object such as sludge can be transported without clogging, liquid can be efficiently separated from the treatment object, and a maintenance operation can be easily conducted. Movable plates 12 and fixed plates 13 are disposed alternately, two screws 21, 22 are disposed in recess sections 14, 15 formed in the movable plates 12 and fixed plates 13, parts of blade sections 25, 26 of the two screws 21, 22 overlap each other, the two screws 21, 22 are rotary driven, and the liquid is discharged from the gap between the movable plates 12 and fixed plates 13, while the treatment object is being transported. When the movable plates 12 are replaced, the two screws 21, 22 are lifted up and then the movable plates 12 are pulled up and replaced.