A pull-on absorbent article 1 includes a front panel 2A, a rear panel 2B, an absorbent assembly 3, and a pair of side seals 4. The rear panel 2B includes a rear extension portion 21b extending downward from the side seals 4. The absorbent assembly 3 includes an oblong absorbent member 33 and a pair of side sheet portions 34 located laterally outwardly from the respective edges of the absorbent member 33 and forming a pair of side gathers 34c in at least the crotch portion C of the article 1. Each side sheet portion 34 has a non-bonded region 34N not bonded to the rear extension portion 21b in a portion thereof overlapping the rear panel and nearer the crotch portion C. Elastic members 36 forming the side gathers 34c extend in the non-bonded region so that the side sheet portion 34 is elasticized in the non-bonded region, too.
