Provided are a method for manufacturing paper with which it is possible to easily manufacture paper wherein water-filterability and yield are excellent and hydrophilia is suppressed without using a cationic polymer or silica, a device for manufacturing an additive for manufacturing paper, and a device for manufacturing paper. The method for manufacturing paper is a method having a reactant generating step for generating a reactant by subjecting an acrylamide polymer to a Hoffman elimination reaction, and a supply step for supplying the reactant to a paper machine within 24 hours of the start of the Hoffman elimination reaction. The acrylamide polymer preferably includes an acrylamide polymer having a intrinsic viscosity of 12.5-28 dl/g and anionization of 0.3 meq/g or less.