A folding device (100) is provided with a conveyance roller (203) which makes contact with both a first region (T1) and a second region (T2) which are located on the same plane, a web guide mechanism (300) which causes the first region (T1) and the second region (T2) to face each other in such a manner that the angle formed between the first region (T1) and the second region (T2) relative to a folding line is reduced toward the downstream side, and a pressing mechanism (400) which presses either the first region (T1) and/or the second region (T2). The pressing mechanism (400) changes the extent to which the pressing mechanism (400) presses webs (61, 62), and changes either the length of a path (first path length (L1)) along which one side edge (10A) is conveyed and/or the length of a path (second path length (L2)) along which the other side edge (20A) is conveyed, the path lengths being defined as lengths on the downstream side of the conveyance roller (203) in the machine direction (MD).
