Intrusion of outside air into duct 31 is restrained without providing as much as possible a contact seal. An apparatus 10 for manufacturing an absorbent body 1, having a recessed form die 21 formed on a predetermined face 20a of a predetermined member 20, moving in one direction along a moving path along the predetermined face 20a； a duct 31 disposed in a predetermined position in the moving path, discharging a gas 3 including fluid absorbent fibers from an opening section 31a toward the predetermined face 20a, an absorbent body 1 being formed by suction of the gas 3 through intake holes at a bottom section of the form die 21 to stack into the form die 21 the fluid absorbent fibers 2 included in the gas 3 when the form die 21 passes by the position of the duct 31. A gap G is formed between the predetermined face 20a and the opening section 31a of the duct 31. A gas pressure inside the duct 31 is lower than a gas pressure outside the duct 31 by suction of the gas 3 from the bottom section of the form die 21. A first wall 43 is outside the duct 31. The first wall 43 is spaced from a wall 33 of the duct 31 by a first spacing S1 and spaced from the predetermined face 20a by a second spacing S2. An outside gas flow along a direction intersecting with the predetermined face 20a and an outside gas flow along the predetermined face 20a is made to reach the gap G by the first wall 43.
