PROBLEM TO BE SOLVED: To prevent a fixing tape from being unfastened, and to prevent the shrinkage in a wide range of the back side section B from occurring while sufficiently ensuring an elastic fitting property of the girth.SOLUTION: On the back side section B, a belt-like sheet 70 which protrudes from both side edges of the back side section B is continuously installed in the width direction. A fastening section 73 is installed on the internal surface of a protruding section 75 from among the protruding sections 75 on both sides in the belt-like sheet 70 and diaper overlapped sections 76 between them. At the same time, both end sections in the width direction from among the diaper overlapped sections 76 are made into free sections 77 which are not fixed to the diaper, and a section between the free sections 77 is made into a fixed section 78 to the diaper. Then, at least the free sections 77 are constituted to be elastically stretchable in the width direction for this disposable diaper.
