PROBLEM TO BE SOLVED: To provide a disposable diaper and a diaper outer, which are equipped with an inner seal portion and an outer seal portion for suppressing the leakage of excrements more from two side portions.SOLUTION: A disposable diaper comprises: extensible inner seal portions 5 and 6 disposed on the two side portions of the side of a top seat 2 and extended in the longitudinal direction and extensible outer seal portions 7 and 8 disposed on the two side portions on the side of a back seat 3 and extended in the longitudinal direction. The extending and shrinking motion forces of second elastic members 7b and 8b for extending and shrinking the outer seal portions 7 and 8 are set stronger than those for extending and shrinking the inner seal portions 5 and 6, and the inner seal portions 5 and 6 are held by the outer seal portions 7 and 8.
