A decanter centrifuge that carries out solid-liquid separation by centrifugal force on an object to be processed that is fed into a rotating bowl and designed from a solid and a saturated solution wherein that solid is dissolved, and discharges solid phase components from a solid discharge opening and discharges liquid phase components from a solvent discharge opening thereof by rotationally operating a screw conveyor disposed within the rotating bowl, the decanter centrifuge being provided with a dilution solvent supply unit for supplying, during centrifuging of the object to be processed, dilution solvent that reduces the concentration of the saturated solution to a discharge path, which is a discharge path for saturated solution moving within the rotating bowl, and which is designed closer to the solvent discharge opening side-than a chamber for supplying the object to be processed.