Yosuke Mori, Ehime, Japan.
Assigned to Daio Paper Corporation, Ehime, Japan.

Filed: 2/26/15
Issued: 9/10/19

An underpants-type disposable diaper, comprising: an outer body having a ventral side outer body and a dorsal side outer body, side edge portions of the ventral side outer body and side edge portions of the dorsal side outer body being joined at both sides in a width direction to form a waist opening; and an inner body extended from a central area of the ventral side outer body in the width direction to a central area of the dorsal side outer body in the width direction so as to pass through a wearer’s crotch, wherein a crotch side edge portion of a central portion of at least one of the ventral side outer body and the dorsal side outer body in the width direction is joined with the inner body to form an inner body joined section, and a part of the at least one of the ventral side outer body and the dorsal side outer body disposed at the crotch side edge portion of the at least one of the ventral side outer body and the dorsal side outer body is folded in a front-back direction once or a few times in a zigzag manner, both lateral side end portions of the crotch side edge portion are fixed in a folded state to constitute non-unfolded parts, a part between the non-unfolded parts is unfixed and unfolded, so that a folded part is formed, the inner body is joined to a portion of the folded part disposed closer to a forward edge than to a fold closest to the forward edge to form the inner body joined section, and the folded part is configured to unfold so that a length in the front-back direction of a side of the at least one of the ventral side outer body and the dorsal side outer body closer to a waist than to the inner body joined section is extensible to a crotch side, and a portion of the inner body disposed closer to the waist than to the inner body joined section can be moved to the crotch side, relative to the at least one of the ventral side outer body and the dorsal side outer body, a length in the front-back direction of a rectangular section of the at least one of the ventral side outer body and the dorsal side outer body is not extended to the crotch side before the diaper is worn, and the length in the front-back direction of the side of the at least one of the ventral side outer body and the dorsal side outer body closer to the waist than to the inner body joined section is naturally extensible to the crotch side when the diaper is worn, so that edges of leg openings in the outer body positioned at lateral sides of the inner body obliquely face up to the side edge portions.