PROBLEM TO BE SOLVED: To provide a pants-type disposable diaper improved in the fitness properties from a gluteal cleft to a crotch and hard to cause a voluminous and swelling feeling in the crotch part when wearing.SOLUTION: Elongated abdominal side curved elastic members 28 reaching the right-hand-side part in the crotch part along the right-leg-side opening part of the main front piece F from the right side seal part 21 of the main front piece F, curving so as to go toward the backside while further going to the central side in the width direction of the crotch part from the right-hand-side part of the crotch part to reach the gluteal cleft facing part positioned at the central part in the width direction of the main back piece B, folding back to the front side in the gluteal cleft facing part and curving so as to go toward the front side while further going to the left to reach the left-hand-side part of the crotch part and reaching the left side seal part 21 of the main front piece F along the left-leg-side opening part of the main front piece F from the left-hand-side part in the crotch part, are fixed in a state stretched in their longitudinal directions at a predetermined stretch ratio. The pants-type disposal diaper is composed in such a way that contraction force acts on parts along the gluteal cleft facing part of the main back piece B and the right-hand-side and the left-hand-side openings in the main front piece F by means of the elongated abdominal side curved elastic members 28.
