A separating device separates liquid absorbent fibers from a material including the liquid absorbent fibers of an absorbent article and impurities. The separating device includes: a case； an insertion port for inserting the material into the case, while the material is made to ride on an airflow； a rotation member housed in the case, the rotation member agitating and opening the material； and a discharge port for discharging the liquid absorbent fibers, of the material that has been opened with the rotation member, from inside the case, while the liquid absorbent fibers are made to ride on an airflow. The rotation member rotates around a center axis that has been set with an axial direction along a predetermined direction from the insertion port to the discharge port, and the rotation member has protruding sections that protrude outward in a direction that intersects with the center axis in a plurality of positions in the axial direction. A regulating member is provided in a predetermined position between the insertion port and the discharge port in the case, and the regulating member regulates movement of the material from the insertion port to the discharge port.
