The purpose of the present invention is to obtain a means capable of stably obtaining anticipated absorbent properties by facilitating web opening, stably and reliably controlling the proportions for mixing the fibers configuring the absorbent to desired proportions and ensuring uniformity of fiber length and blend. Namely, when manufacturing an absorbent comprising at least a cellulose water-absorbing fiber with a thermoplastic resin fiber, an absorbent manufacturing method comprises: a web-forming step for forming a web (2) of a constant thickness without thermal fusion of the fibers by laminating each of multiple fiber groups containing at least one constituent fiber in previously set proportions an opening step for opening said web (2) that is continuously conveyed from the web-forming step to form an absorbent material (4) and a shaping step for shaping the absorbent (6) by fiber-stacking the absorbent material (4) formed by the opening step.
