A binding method of a perfect-bound booklet includes the steps of folding each leaf of sheets forming a body to obtain multiple signatures; pressing creased parts of the multiple signatures in a thickness direction thereof; jogging a one-book bundle formed of a predetermined number of signatures forming a body, a front cover, and a back cover, or a multi-book bundle formed by stacking a plurality of one-book bundles on top of one another; applying a first adhesive that remains flexible upon curing, in a layer in a middle area 5 to 10 millimeters from both top and bottom ends of a rear face of the one-book bundle or the multi-book bundle; applying a second adhesive on the entire rear face; and drying and curing the second adhesive for a predetermined drying time.