A method of manufacturing a top sheet material or back sheet material for use in the manufacture of disposable absorbent articles including the steps of: a) splitting a continuous first web of sheet material having substantially straight side edges into a second and third continuous web by an alternating concave-convex cutting line cut in a longitudinal direction along the continuous first web, the cutting line being distanced from both side edges of the continuous first web; b) shifting the second continuous web in a lateral direction in relation to the third continuous web so that the substantially straight edges of the second and third continuous webs are parallel to and adjacent to each other and longitudinally shifting the second continuous web so that the series of concave edge portions and the series of convex edge portions of the second and third continuous webs are longitudinally aligned with each other; c) directly or indirectly joining the substantially straight edges of the second and third continuous webs to each other, thereby forming a composite fourth web. The cutting line is made in the first continuous web so that all portions of the cutting line are distanced from a longitudinal center line of the first continuous web.