PROBLEM TO BE SOLVED: To provide a pants-type disposable diaper, which improves fitness from the gluteal cleft to the crotch, and the crotch area of which is less likely to be bulky when worn.SOLUTION: A bent fit portion 40, which is bent so as to enter the gluteal cleft of a wearer by contracting in the width direction, is provided in a gluteal cleft facing portion of a back section B. Each of elongated and curved ventral elastic members 28 leads from a right side seal portion 21 of a front section F along a right leg opening to the right side of the gluteal cleft facing portion changes direction forward while crossing the gluteal cleft facing portion in the width direction from right to left and leads from the left side of the gluteal cleft facing portion along a left leg opening to a left side seal portion 21 of the front section F. The ventral elastic members 28 are fixed in a state of being extended by a predetermined elongation rate in their longitudinal direction, and exert a contractile force on a portion along the right and left leg openings at least from the front section F to the side of the gluteal cleft facing portion of the back section B.
