PROBLEM TO BE SOLVED: To provide an inexpensive nonwoven fabric having engagement force and softness which are required for practical use while having a less basis weight than a conventional nonwoven fabric.SOLUTION: A diaper back sheet is produced by partly applying tension to a spunbonded raw nonwoven fabric P so that low-density parts 2 are formed, and so that high-density parts 3 are appropriately retained. The low density parts 2 are formed as follows. On the peripheral surfaces of rollers 110 and 110 along rotation directions, grooves are formed at a prescribed pitch in the width directions of the rollers 110 and 110, so that protrusions 112 and 112 and recesses 113 and 113 are alternately formed in a repeated manner in the respective width directions. The rollers 110 and 110 face each other and are rotated in opposite directions in such a way that the recesses 113 (protrusions 112) on one of the rollers mesh with the protrusions 112 (recesses 113) on the other of the rollers. A nonwoven fabric P unwound from the spunbonded raw nonwoven fabric P is allowed to pass through between the two rollers 110 and 110, and thereby the low-density parts 2 are formed on side surfaces when the recesses 113 (protrusions 112) mesh with the protrusions 112 (recesses 113).
