Provided is a method for producing pulp fibers to be saccharified, whereby it becomes possible to reduce the amount of a highly water-absorbable polymer and therefore increase the collection efficiency in the production of a saccharified solution when pulp fibers for a saccharified liquid is produced from a dirty absorbent article. The method is a method for producing pulp fibers to be saccharified, from pulp fibers in a dirty absorbent article. The method includes: a solid-liquid separation step (S18) of crushing up a highly water-absorbable polymer while separating an inactivated aqueous solution containing pulp fibers and the highly water-absorbable polymer both separated from a dirty absorbent article into a solid material (98) containing the pulp fibers and the highly water-absorbable polymer and a liquid material (E) containing the highly water-absorbable polymer and the inactivated aqueous solution; and a removal step (S21) of washing away the remaining highly water-absorbable polymer by washing the separated solid pulp fibers in a solution or another means to produce pulp fibers to be saccharified.