A pants-type disposable diaper (1, 1a, 1b) which has a waist opening at an upper end and a pair of leg openings on a lower part, comprising: an outer covering sheet (4, 4b) which is folded in a middle part lying between a front part and a back part, said front part and said back part being to be positioned on a front side and a back side of a wearer, left and right ends of said front part being bonded to left and right ends of said back part, respectively, to form a waist opening at upper ends of said front part and said back part and form a pair of leg openings under said front part and said back part, said pair of leg openings lying in left and right of said middle part; and a sheet-like absorbent body (20, 20a) having a sheet-like main body part and a pair of side sheets located on both side portions of the main body part in the diaper width direction which is attached on an inner surface of said outer covering sheet (4, 4b) to contact with said wearer and absorb excrement from said wearer, said absorbent body (20; 20a) lying from said front part to said back part and the main body part comprising a back sheet, an absorbent core and a top sheet; wherein the back sheet is bonded on the outer covering sheet and said absorbent core is located between said top sheet and said back sheet, wherein one end portion of said absorbent body (20; 20a) in a longitudinal direction thereof which is positioned in said front part or said back part is folded toward said inner surface of said outer covering sheet (4, 4b) to be bonded on said inner surface, whereby said back sheet positioned between said inner surface of the outer covering sheet (4, 4b) and said absorbent core and said top sheet positioned on an inner surface of said absorbent core are longer than the absorbent core with respect to the longitudinal direction of said sheet-like absorbent body (20, 20a), characterized in that an end portion of the back sheet and the top sheet are overlapped and bonded to each other, and said bonded end portion is folded so that a surface of the top sheet is bonded to the inner surface of the outer covering sheet (4, 4b). an outer covering sheet (4, 4b) which is folded in a middle part lying between a front part and a back part, said front part and said back part being to be positioned on a front side and a back side of a wearer, left and right ends of said front part being bonded to left and right ends of said back part, respectively, to form a waist opening at upper ends of said front part and said back part and form a pair of leg openings under said front part and said back part, said pair of leg openings lying in left and right of said middle part; and a sheet-like absorbent body (20, 20a) having a sheet-like main body part and a pair of side sheets located on both side portions of the main body part in the diaper width direction which is attached on an inner surface of said outer covering sheet (4, 4b) to contact with said wearer and absorb excrement from said wearer, said absorbent body (20; 20a) lying from said front part to said back part and the main body part comprising a back sheet, an absorbent core and a top sheet; wherein the back sheet is bonded on the outer covering sheet and said absorbent core is located between said top sheet and said back sheet, wherein one end portion of said absorbent body (20; 20a) in a longitudinal direction thereof which is positioned in said front part or said back part is folded toward said inner surface of said outer covering sheet (4, 4b) to be bonded on said inner surface, whereby said back sheet positioned between said inner surface of the outer covering sheet (4, 4b) and said absorbent core and said top sheet positioned on an inner surface of said absorbent core are longer than the absorbent core with respect to the longitudinal direction of said sheet-like absorbent body (20, 20a), characterized in that an end portion of the back sheet and the top sheet are overlapped and bonded to each other, and said bonded end portion is folded so that a surface of the top sheet is bonded to the inner surface of the outer covering sheet (4, 4b).