An absorbent sheet manufacturing apparatus has a cylinder part having a plurality of concave portions arranged in a circumferential direction, a particle filling part which is located above the cylinder part and which stores particles of high-absorbent resin, to sequentially fill the plurality of concave portions with particles by a particle filling opening in its lower end, and a communication part which is located adjacent to the particle filling opening. A concave portion facing a posterior edge of the particle filling opening is brought into communication with external space through the communication part. Therefore, when particles are filled into the concave portion from the particle filling part, air in the concave portion is forced out by particles entering the concave portion and is easily discharged to the external space through the communication part. As a result, it is possible to increase a density of particles filled in the concave portion.