A pull-on absorbent article (1) includes a front panel (2A), a rear panel (2B), and an absorbent assembly (3) fixed to them so as to bridge them. Each of the front panel (2A) and the rear panel (2B) includes a body portion (20a, 20b) including side seals (4) at both lateral sides and an extension portion (21a, 21b) extended toward a crotch section (C). The absorbent assembly (3) includes an absorbent member (33) and side sheet portions (34) located outward of both edges in the longitudinal direction of the absorbent member (33). The side sheet portion (34) includes a stretchable region (34c) having stretchability due to an elastic member (36) fixed in a stretched state at least at the crotch section (C). In the stretchable region (34c), a length Lm from the center line (CL) of the article to a front end part (34m) is larger than a length Lu from the center line (CL) to a rear end part (34u).
