This disposable diaper includes a sweat-absorbent sheet attached to the inner side of the diaper to maintain its sweat-absorbing function during use of the diaper. The inner side of front or rear waist region constituting the disposable diaper is covered with a hydrophobic sheet and the sweat-absorbent sheet is bonded to the inner surface of the hydrophobic sheet. The hydrophobic sheet has a first sealing-free zone extending, inclusive of a first lower edge, in a circumferential direction so as to be left free from the inner side of the diaper and a first sealing zone extending above the first sealing-free zone and bonded to the inner side of the diaper. The sweat-absorbent sheet has a second lower edge extending in the circumferential direction above the first lower edge of the hydrophobic sheet, a second sealing-free zone extending, inclusive of the second lower edge, in the circumferential direction so as to be left free from the hydrophobic sheet and a second sealing zone extending above the second sealing-free zone and bonded to the hydrophobic sheet. A lower end of the first sealing zone is provided so as to lie below a lower end of the second sealing zone.