PROBLEM TO BE SOLVED: To provide an underpants type disposable diaper excelling in fitting property at a gluteal cleft and on both sides of its width direction and hardly causing turn-up of the edges of leg openings in a rear part.SOLUTION: The underpants type disposable diaper 1 includes back side curved elastic members 26 and gluteal cleft part width direction elastic members 27 of which only the portions located on the width direction center side of side overlap parts 41 near the side of a gluteal cleft facing part are cut fine and made non-contracting parts 43 to which contractive force is not applied. The gluteal cleft part width direction elastic members 27 are fixed to an outer sheet 20 at a stretch ratio lower at edge side portions 46 located on the width direction outside of boundary parts 45 extending close to both width direction sides of boundaries between side overlap parts 41 and side extended parts 42, and at intermediate parts 47 located between the boundary parts 45 and the non-contracting parts 43, than at main parts located at the gluteal cleft facing parts, and at the boundary parts 45.
