A method for reducing the thickness of an absorption body having liquid absorptive fibers and a highly absorptive polymer. The method involves (1) conveying the absorption body by moving the absorption body while holding the absorptive body on a holding surface by sucking gas from gas suction holes in the holding surface, and (2) reducing the thickness of the absorption body by sucking a belt member, which is disposed so as to face the movement path of the holding surface and so as to be able to move along the movement path within a predetermined range of the movement path, in the predetermined range toward the holding surface by sucking gas from the gas suction holes and sandwiching the absorption body between the holding surface and the belt member.
