A separating device separates liquid absorbent fibers fromimpurities. The separating device includes: a case； an insertion portfor inserting the material into the case, while the material is madeto ride on an airflow； a rotation member for agitating and opening thematerial； and a discharge port for discharging the liquid absorbentfibers . The rotation member rotates around a center axis and hasprotruding sections that protrude outward in a direction that intersectswith the center axis in a plurality of positions in the axial direction.A regulating member is provided between the insertion port and thedischarge port in the case, that regulates movement of the materialfrom the insertion port to the discharge port.
