A gravitational settling tank including a pressure vessel which precipitates solid content contained in slurry in which coal and solvent are blended, and separates the solid-content concentrated liquid from the supernatant liquid, and a supply pipe which supplies the pressure vessel with the slurry. A main body part and a nozzle part which is connected on the downstream side of the main body part and extends horizontally are provided in the supply pipe. A plurality of holes are provided in the nozzle part. By virtue of this, agitation of the solid-content concentrated liquid which has settled in the bottom is inhibited.