A method of manufacturing a stretchable composite sheet, by setting a plurality of nip areas arranged along a transport direction of a first continuous sheet, the first continuous sheet being transported while being sandwiched between rotating rolls in the nip areas, and by passing through the nip areas, as the first continuous sheet, a sheet in which stretchability is developed in the transport direction by being extended in the transport direction, including: extending the first continuous sheet in the transport direction, while transporting the first continuous sheet from a first nip area to a second nip area, the first continuous sheet being either a sheet in which stretchability has already been developed or a sheet in which stretchability has yet to be developed forming an opening in the first continuous sheet intermittently in the transport direction, while transporting the first continuous sheet from the second nip area to a third nip area, the first continuous sheet being in a state of having been extended in the extending and adhering in an overlapping manner a second continuous sheet having a lower stretchability than the first continuous sheet to the first continuous sheet, in the third nip area.
