Here is disclosed a composite sheet comprising substantially non-stretchable
nonwoven fabric sheets and a plurality of elastic members extending in a transverse
direction and spaced one from another in a longitudinal direction by a given spacing
wherein the elastic members are secured in a stretched state to the nonwoven fabric
sheets. The composite sheet has a plurality of gathers formed by slightly undulated
surface of the nonwoven fabric sheets and the elastic members and these gathers
are substantially continuous in the longitudinal direction and arranged at substantially
regular intervals in the transverse direction.