A manufacturing method of an absorbent body used for an absorbent article, includes molding the absorbent body by sucking in a gas, mixed with a liquid absorbent fiber and a superabsorbent polymer, using a suction hole at a bottom portion of a mold, and laminating the liquid absorbent fiber and the superabsorbent polymer on the bottom portion, and making a lamination thickness of the absorbent body thin by sucking out gas in the absorbent body placed on a placement surface on which the absorbent body is placed by, after the molding, in a state in which the gas is not supplied, sucking air through the suction hole on the placement surface, and creating an air pressure, in a space in between fibers in the absorbent body while sucking out the air, lower than that in a space in between fibers in the absorbent body while laminating in molding.