An apparatus for manufacturing an absorbent body, including a recessed form die formed on a predetermined face of a predetermined member, moving in one direction along a moving path along the predetermined face a duct disposed in a predetermined position in the moving path, discharging a gas including fluid absorbent fibers from an opening section toward the predetermined face and a polymer casting member disposed inside the duct, casting a superabsorbent polymer from a casting opening toward a center area of the opening section in a direction along the moving path, wherein in the case of the form die passing the duct position, by the gas being sucked through air intake holes in a bottom section of the form die, the fluid absorbent fibers and the superabsorbent polymer in the gas are stacked in the form die to form an absorbent body, wherein an air pressure inside the duct is made lower than the air pressure outside the duct because of the gas being sucked through the bottom section of the form die, wherein a duct-inner-wall section is inside the duct and is disposed facing an inner wall face of a wall section of the duct with a spacing therebetween, the wall section having a gap between the predetermined face and the opening section of the duct, and an outside air intrudes into the duct along the moving path through the gap, and the duct-inner-wall section restricts the outside air intruding into the duct through the gap flowing into the center area of the duct.
