Provided is a method for producing a disposable underwear-type diaper, by which disposable underwear-type diapers provided with a fastener having no seam in a middle portion can be continuously produced. Fasteners (20) folded in two are arranged on one main surface (12a) of a first continuous body (12) so that ends (23, 25) of the fasteners (20) are arranged on the outside of the one main surface (12a). A second continuous body (14) is laid over another main surface (12b) of the first continuous body (12) in a state where one end (23) is bent so as to be laid over the other main surface (12b), and the first continuous body (12) and second continuous body (14) are bonded together to form a composite continuous body (16) to which the one end (23) of the fasteners (20) is fixed. The composite continuous body (16) is cut to form a piece (18) on which the pair of fasteners (20) are arranged only in a first region (18a). The piece (18) is folded in two along an imaginary line (18x) and overlapped, following which the other end (25) of the fasteners (20) is bent and laid over and fixed to a second region (18b).
